U.S. patent application number 11/259166 was filed with the patent office on 2006-05-04 for specular gloss simulation device, specular gloss simulation method, control program for specular gloss simulation device and storage medium thereof.
This patent application is currently assigned to Sharp Kabushiki Kaisha. Invention is credited to Hiroshi Doshoda, Yoichi Miyake.
Application Number | 20060092412 11/259166 |
Document ID | / |
Family ID | 36261413 |
Filed Date | 2006-05-04 |
United States Patent
Application |
20060092412 |
Kind Code |
A1 |
Doshoda; Hiroshi ; et
al. |
May 4, 2006 |
Specular gloss simulation device, specular gloss simulation method,
control program for specular gloss simulation device and storage
medium thereof
Abstract
The present invention realizes a specular gloss simulation
device which can accurately simulate, by using a Bidirectional
Reflectance Distribution Function, specular glossiness of an image
even if the image has a low density and low gloss. A specular gloss
simulation device according to the present invention is for
simulating specular glossiness by simulating a specular reflection
light amount in each (other) geometry from a luminance measured in
a given geometry of a sample having a base material and a colorant
material layer formed on the base material. A specular gloss
simulation device 100 is provided with a lower layer reflection
light component calculating section 111 for calculating a lower
layer reflection light component, which is reflected on a base
material and travels through and out of a color layer, an internal
reflection light component creating section 112 for creating an
internal reflection light component, which is reflected from an
interior of the colorant material layer, a surface reflection light
component creating section 113 for creating a surface reflection
light component, which is reflected on a surface of the colorant
material layer, and a specular reflection light amount calculating
section 114 for obtaining a specular reflection light amount of the
sample by adding up the components thus created by each
section.
Inventors: |
Doshoda; Hiroshi;
(Chiba-shi, JP) ; Miyake; Yoichi; (Sakura-shi,
JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
Sharp Kabushiki Kaisha
|
Family ID: |
36261413 |
Appl. No.: |
11/259166 |
Filed: |
October 27, 2005 |
Current U.S.
Class: |
356/243.1 |
Current CPC
Class: |
G01J 3/504 20130101;
G01N 21/57 20130101 |
Class at
Publication: |
356/243.1 |
International
Class: |
G01J 1/10 20060101
G01J001/10 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 29, 2004 |
JP |
2004-316933 |
Jul 20, 2005 |
JP |
2005-210525 |
Claims
1. A specular gloss simulation device for simulating specular gloss
by measuring, in a given geometry, luminance of a sample that has a
base material and a colorant material layer formed on the base
material, and then simulating a specular reflection light amount in
an other geometry from the thus measured luminance, the specular
gloss simulation device comprising: a lower layer reflection light
component creating section for calculating a lower layer reflection
light component from base material luminance, where the base
material luminance is luminance of only the base material measured
in a plurality of geometries, and the lower layer reflection light
component is a component being reflected on the base material and
transmitting through and out of the colorant material layer; an
internal reflection light component creating section for measuring
luminance of the sample in the given geometry, and for creating an
internal reflection light component from the measured luminance and
the lower layer reflection light component, where the internal
reflection light component is a component being reflected from an
interior of the colorant material layer; a surface reflection light
component creating section for measuring luminance of the sample in
the given geometry, and for creating a surface reflection light
component from the measured luminance, the lower layer reflection
light component, and the internal reflection light component, where
the surface reflection light component is a component being
reflected on a surface of the colorant material layer; and a
specular reflection light amount calculating section for obtaining
a specular reflection light amount of the sample from the
components thus created by the lower layer reflection light
component creating section, internal reflection light component
creating section, and surface reflection light component creating
section.
2. A specular gloss simulation device as set forth in claim 1,
wherein: the lower layer reflection light component creating
section measures the base material luminance in the plurality of
geometries, and calculates out the lower layer reflection light
component from the thus measured luminance; the internal reflection
light component creating section measures the luminance of the
sample in a non-specular reflection geometry, calculates out the
internal reflection light component from the thus measured
luminance and the lower layer reflection light component, and
simulates an internal reflection light component in the other
geometry by using a Bidirectional Reflectance Distribution Function
model; and the surface reflection light component creating section
measures the luminance of the sample in a specular reflection
geometry, calculates out the surface reflection light component
from the thus measured luminance, the lower layer reflection light
component, and the internal reflection light component, and
simulates the surface reflection light component in an other
specular reflection geometry than the geometry by using a
Bidirectional Reflectance Distribution Function model.
3. A specular gloss simulation device as set forth in claim 2,
wherein: the Bidirectional Reflectance Distribution Function model
used by the surface reflection light component creating section for
simulating the surface reflection light component in the other
geometry is a Torrance-Sparrow model.
4. A specular gloss simulation device as set forth in claim 2,
wherein: the Bidirectional Reflectance Distribution Function model
used by the internal reflection light component creating section
for simulating the internal reflection light component in the other
geometry is an Oren-Nayar model.
5. A specular gloss simulation device as set forth in claim 2,
wherein: the lower layer reflection light component creating
section calculates out the lower layer reflection light component
from the measured luminance of the base material, and transmittance
and refractive index of the colorant material layer.
6. A specular gloss simulation device as set forth in claim 2,
wherein: the internal reflection light component creating section
also functions as a diffuse reflection light component creating
section for simulating diffuse reflection light component which is
a component being diffused among colorant material particles
contained in the colorant material layer and transmitting out of
the colorant material layer; the internal reflection light
component creating section comprises: a colorant material particle
reflection light component creating section (a) for measuring
luminance of the sample in the specular reflection geometry, (b)
for calculating out a colorant material particle reflection light
component from the thus measured luminance, the lower layer
reflection light component, and the diffuse reflection light
component, and (c) for simulating a colorant material particle
reflection light component in the other geometry by using the
Bidirectional Reflectance Distribution Function model, where the
colorant material particle reflection light component is a
component reflected from the colorant material particles; and a
shape parameter calculating section for deciding a mixing ratio
between the colorant material particle reflection light component
and the surface reflection light component from the results of the
calculations performed by the surface reflection light component
creating section and the colorant material particle reflection
light component creating section, and the thus measured luminance
of the sample in the specular reflection geometry, and the specular
reflection light amount calculating section obtains the specular
reflection light amount by adding up the components thus created
respectively by the lower layer reflection light component creating
section, diffuse reflection light component creating section, and
the components which are created respectively by the colorant
material particle reflection light component creating section and
the surface reflection light component creating section and whose
mixing ratio is decided by the shape parameter calculating
section.
7. A specular gloss simulation device as set forth in claim 6,
wherein: the surface reflection light component creating section
uses a Torrance-Sparrow model as the Bidirectional Reflectance
Distribution Function, and uses, in the Torrance-Sparrow model, a
variable of surface roughness of the sample as a parameter for
defining an extent of a reflection light component.
8. A specular gloss simulation device as set forth in claim 6,
wherein: the colorant material particle reflection light component
creating section uses a Torrance-Sparrow model as the Bidirectional
Reflectance Distribution Function, and uses, in the
Torrance-Sparrow model, a variable of density distribution evenness
of the sample as a parameter for defining an extent of a reflection
light component.
9. A specular gloss simulation device for simulating specular gloss
by measuring, in a given geometry, luminance of a sample that has a
base material and a colorant material layer formed on the base
material, and then simulating a specular reflection light amount in
an other geometry from the thus measured luminance, the specular
gloss simulation device comprising: a lower layer reflection light
component creating section for calculating a lower layer reflection
light component from base material luminance, where the base
material luminance is luminance of only the base material measured
in a plurality of geometries, and the lower layer reflection light
component is a component being reflected on the base material and
transmitting through and out of the colorant material layer; an
internal reflection light component creating section for creating
an internal reflection light component from luminance of the sample
and the lower layer reflection light component, where the internal
reflection light component is a component being reflected from an
interior of the colorant material layer, and the luminance of the
sample is measured in the given geometry; a surface reflection
light component creating section for creating a surface reflection
light component from the luminance of the sample, the lower layer
reflection light component, and the internal reflection light
component, where the surface reflection light component is a
component being reflected on a surface of the colorant material
layer, and the luminance of the sample is measured in the given
geometry; and a specular reflection light amount calculating
section for obtaining a specular reflection light amount of the
sample from the components thus created by the lower layer
reflection light component creating section, internal reflection
light component creating section, and surface reflection light
component creating section.
10. A specular gloss simulation device for simulating specular
gloss by measuring, in a given geometry, luminance of a sample that
has a base material and a colorant material layer which is formed
on the base material and contains colorant material particles, and
then simulating a specular reflection light amount in an other
geometry from the thus measured luminance, the specular gloss
simulation device comprising: a lower layer reflection light
component creating section for calculating lower layer reflection
light components in the given geometry and the other geometry from
base material luminance, where the base material luminance is
luminance of only the base material measured in a plurality of
geometries, and the lower layer reflection light component is a
component being reflected on the base material and transmitting
through and out of the colorant material layer; an upper layer
reflection light component creating section for calculating a
diffuse reflection light component, a colorant material particle
reflection light component, and a surface reflection light
component in the other geometry from the luminance of the sample
measured in the given geometry and the lower layer reflection light
component in the given geometry, the lower layer reflection light
component being calculated out by the lower layer reflection light
component creating section, where the diffuse reflection light
component is a component being diffused among the colorant material
particles contained in the colorant material layer and transmitting
out of the colorant material layer, the colorant material particle
reflection light component is a component being reflected on the
colorant material particles, and the surface reflection light
component is a component being reflected on a surface of the
colorant material layer; and a specular reflection light amount
calculating section for calculating out a specular reflection light
amount of the sample in the other geometry from the components in
the other geometry which are thus calculated out by the lower layer
reflection light component creating section and the upper layer
reflection light component creating section.
11. A specular gloss simulation device as set forth in claim 10,
wherein: the upper reflection light component creating section
calculates out the diffuse reflection light component, the colorant
material particle reflection light component, and the surface
reflection light component in the other geometry by using a
Bidirectional Reflectance Distribution Function model.
12. A specular gloss simulation device as set forth in claim 11,
wherein: the lower layer reflection light component creating
section calculates out the lower layer reflection light components
in the other geometry and at least three kinds of the given
geometries; the upper layer reflection light component creating
section includes: a parameter calculating section for deciding (a)
a parameter to be used in the Oren-Nayar model, and (b) a mixing
ratio among the diffuse reflection light component, the colorant
material particle reflection light component, and the surface
reflection light component, from (i) luminance of the sample
measured in the at least three kinds of the given geometries, and
(ii) the lower layer reflection light components in the at least
three kinds of the given geometries, the lower layer reflection
light components being calculated by the lower layer reflection
light component creating section; and a reflection light component
calculating section for calculating the colorant material particle
reflection light component and the surface reflection light
component in the other geometry according to the mixing ratio, and
calculating the diffuse reflection light component in the other
geometry according to the mixing ratio and from the parameter by
using the Oren-Nayar model.
13. A specular gloss simulation device as set forth in claim 12,
wherein: the reflection light component calculating section
calculates the colorant material particle reflection light
component and the surface reflection light component in the other
geometry according to the mixing ratio and by using the
Torrance-Sparrow model.
14. A specular gloss simulation method for simulating specular
gloss by simulating a specular reflection light amount of a sample
having a base material and a colorant material layer formed on the
base material, the method comprising: (i) creating a lower layer
reflection light component by calculating out the lower layer
reflection light component from base material luminance where the
base material luminance is luminance of only the base material
measured in a plurality of geometries which are varied in incident
light angle and reflection light angle by a constant angle, the
lower layer reflection light component is a component being
reflected on the base material and transmitting through and out of
the colorant material layer; (ii) creating an internal refection
light component by simulating, by using a Bidirectional Reflectance
Distribution Function model, the internal refection light component
in the other geometry from an internal reflection light component
calculated out from luminance of the sample measured in one
non-specular reflection geometry and the lower layer reflection
light component, where the internal reflection light component is a
component being reflected from an interior of the colorant material
layer; (iii) creating a surface reflection light component by
simulating, by using a Bidirectional Reflectance Distribution
Function model, the surface reflection light component in the other
geometry from a surface reflection light component calculated out
from luminance of the sample measured in one non-specular
reflection geometry, the lower layer reflection light component,
and the internal reflection light component, where the surface
reflection light component is a component being reflected on a
surface of the colorant material layer; and (iv) calculating out a
specular reflection light amount of the sample from the lower layer
reflection light component, internal reflection light component,
and surface reflection light component thus obtained.
15. A specular gloss simulation method for simulating specular
gloss by simulating a specular reflection light amount of a sample
having a base material and a colorant material layer which is
formed on the base material and contains colorant material
particles, the method comprising: (i) creating lower layer
reflection light components in the given geometry and the other
geometry by calculating out the lower layer reflection light
components from base material luminance where the base material
luminance is luminance of only the base material measured in a
plurality of geometries, the lower layer reflection light component
is a component being reflected on the base material and
transmitting through and out of the colorant material layer; (ii)
calculating out a diffuse reflection light component, a colorant
material particle reflection light component, and a surface
reflection light component from the luminance of the sample
measured in the given geometry and the lower layer reflection light
component in the given geometry, the lower layer reflection light
component being calculated out in the step (i), where the diffuse
reflection light component is a component being diffused among the
colorant material particles contained in the colorant material
layer and transmitting out of the colorant material layer, the
colorant material particle reflection light component is a
component being reflected on the colorant material particles, and
the surface reflection light component is a component being
reflected on a surface of the colorant material layer; and (iii)
calculating out a specular reflection light amount of the sample in
the other geometry from the diffuse reflection light component, the
lower layer reflection light component in the other geometry, which
is thus calculated in the step (i) and the colorant material
particle reflection light component, and the surface reflection
light component thus calculated in the step (ii).
16. A control program for operating a specular gloss simulation
device for simulating specular gloss by measuring, in a given
geometry, luminance of a sample having a base material and a
colorant material layer formed on the base material, and then
simulating a specular reflection light amount in an other geometry
from the thus measured luminance, the specular gloss simulation
device comprising: a lower layer reflection light component
creating section for calculating a lower layer reflection light
component from base material luminance, where the base material
luminance is luminance of only the base material measured in a
plurality of geometries, and the lower layer reflection light
component is a component being reflected on the base material and
transmitting through and out of the colorant material layer; an
internal reflection light component creating section for measuring
luminance of the sample in the given geometry, and for creating an
internal reflection light component from the measured luminance and
the lower layer reflection light component, where the internal
reflection light component is a component being reflected from an
interior of the colorant material layer; a surface reflection light
component creating section for measuring luminance of the sample in
the given geometry, and for creating a surface reflection light
component from the measured luminance, the lower layer reflection
light component, and the internal reflection light component, where
the surface reflection light component is a component being
reflected on a surface of the colorant material layer; and a
specular reflection light amount calculating section for obtaining
a specular reflection light amount of the sample from the
components thus created by the lower layer reflection light
component creating section, internal reflection light component
creating section, and surface reflection light component creating
section, and the control program causing a computer to function as
each of the sections.
17. A control program for operating a specular gloss simulation
device for simulating specular gloss by measuring, in a given
geometry, luminance of a sample having a base material and a
colorant material layer formed on the base material, and then
simulating a specular reflection light amount in an other geometry
from the thus measured luminance, the specular gloss simulation
device comprising: a lower layer reflection light component
creating section for calculating a lower layer reflection light
component from base material luminance, where the base material
luminance is luminance of only the base material measured in a
plurality of geometries, and the lower layer reflection light
component is a component being reflected on the base material and
transmitting through and out of the colorant material layer; an
internal reflection light component creating section for creating
an internal reflection light component from luminance of the sample
and the lower layer reflection light component, where the internal
reflection light component is a component being reflected from an
interior of the colorant material layer, and the luminance of the
sample is measured in the given geometry; a surface reflection
light component creating section for creating a surface reflection
light component from the luminance of the sample, the lower layer
reflection light component, and the internal reflection light
component, where the surface reflection light component is a
component being reflected on a surface of the colorant material
layer, and the luminance of the sample is measured in the given
geometry; and a specular reflection light amount calculating
section for obtaining a specular reflection light amount of the
sample from the components thus created by the lower layer
reflection light component creating section, internal reflection
light component creating section, and surface reflection light
component creating section, and the control program causing a
computer to function as each of the sections.
18. A control program for operating a specular gloss simulation
device for simulating specular gloss by measuring, in a given
geometry, luminance of a sample having a base material and a
colorant material layer which is formed on the base material and
contains colorant material particles, and then simulating a
specular reflection light amount in an other geometry from the thus
measured luminance, the specular gloss simulation device
comprising: a lower layer reflection light component creating
section for calculating lower layer reflection light components in
the given geometry and the other geometry from base material
luminance, where the base material luminance is luminance of only
the base material measured in a plurality of geometries, and the
lower layer reflection light component is a component being
reflected on the base material and transmitting through and out of
the colorant material layer; an upper layer reflection light
component creating section for calculating a diffuse reflection
light component, a colorant material particle reflection light
component, and a surface reflection light component in the other
geometry from the luminance of the sample measured in the given
geometry and the lower layer reflection light component in the
given geometry, the lower layer reflection light component being
calculated out by the lower layer reflection light component
creating section, where the diffuse reflection light component is a
component being diffused among the colorant material particles
contained in the colorant material layer and transmitting out of
the colorant material layer, the colorant material particle
reflection light component is a component being reflected on the
colorant material particles, and the surface reflection light
component is a component being reflected on a surface of the
colorant material layer; and a specular reflection light amount
calculating section for calculating out a specular reflection light
amount of the sample in the other geometry from the components in
the other geometry which are thus calculated out by the lower layer
reflection light component creating section and the upper layer
reflection light component creating section, and the control
program causing a computer to function as each of the sections.
19. A computer-readable storage medium in which a control program
is stored, the control program being for operating a specular gloss
simulation device for simulating specular gloss by measuring, in a
given geometry, luminance of a sample having a base material and a
colorant material layer formed on the base material, and then
simulating a specular reflection light amount in an other geometry
from the thus measured luminance, the specular gloss simulation
device comprising: a lower layer reflection light component
creating section for calculating a lower layer reflection light
component from base material luminance, where the base material
luminance is luminance of only the base material measured in a
plurality of geometries, and the lower layer reflection light
component is a component being reflected on the base material and
transmitting through and out of the colorant material layer; an
internal reflection light component creating section for measuring
luminance of the sample in the given geometry, and for creating an
internal reflection light component from the measured luminance and
the lower layer reflection light component, where the internal
reflection light component is a component being reflected from an
interior of the colorant material layer; a surface reflection light
component creating section for measuring luminance of the sample in
the given geometry, and for creating a surface reflection light
component from the measured luminance, the lower layer reflection
light component, and the internal reflection light component, where
the surface reflection light component is a component being
reflected on a surface of the colorant material layer; and a
specular reflection light amount calculating section for obtaining
a specular reflection light amount of the sample from the
components thus created by the lower layer reflection light
component creating section, internal reflection light component
creating section, and surface reflection light component creating
section, and the control program causing a computer to function as
each of the sections.
20. A computer-readable storage medium in which a control program
is stored, the control program being for operating a specular gloss
simulation device for simulating specular gloss by measuring, in a
given geometry, luminance of a sample having a base material and a
colorant material layer formed on the base material, and then
simulating a specular reflection light amount in an other geometry
from the thus measured luminance, the specular gloss simulation
device comprising: a lower layer reflection light component
creating section for calculating a lower layer reflection light
component from base material luminance, where the base material
luminance is luminance of only the base material measured in a
plurality of geometries, and the lower layer reflection light
component is a component being reflected on the base material and
transmitting through and out of the colorant material layer; an
internal reflection light component creating section for creating
an internal reflection light component from luminance of the sample
and the lower layer reflection light component, where the internal
reflection light component is a component being reflected from an
interior of the colorant material layer, and the luminance of the
sample is measured in the given geometry; a surface reflection
light component creating section for creating a surface reflection
light component from the luminance of the sample, the lower layer
reflection light component, and the internal reflection light
component, where the surface reflection light component is a
component being reflected on a surface of the colorant material
layer, and the luminance of the sample is measured in the given
geometry; and a specular reflection light amount calculating
section for obtaining a specular reflection light amount of the
sample from the components thus created by the lower layer
reflection light component creating section, internal reflection
light component creating section, and surface reflection light
component creating section, and the control program causing a
computer to function as each of the sections.
21. A computer-readable storage medium in which a control program
is stored, the control program being for operating a specular gloss
simulation device for simulating specular gloss by measuring, in a
given geometry, luminance of a sample having a base material and a
colorant material layer which is formed on the base material and
contains colorant material particles, and then simulating a
specular reflection light amount in an other geometry from the thus
measured luminance, the specular gloss simulation device
comprising: a lower layer reflection light component creating
section for calculating lower layer reflection light components in
the given geometry and the other geometry from base material
luminance, where the base material luminance is luminance of only
the base material measured in a plurality of geometries, and the
lower layer reflection light component is a component being
reflected on the base material and transmitting through and out of
the colorant material layer; an upper layer reflection light
component creating section for calculating a diffuse reflection
light component, a colorant material particle reflection light
component, and a surface reflection light component in the other
geometry from the luminance of the sample measured in the given
geometry and the lower layer reflection light component in the
given geometry, the lower layer reflection light component being
calculated out by the lower layer reflection light component
creating section, where the diffuse reflection light component is a
component being diffused among the colorant material particles
contained in the colorant material layer and transmitting out of
the colorant material layer, the colorant material particle
reflection light component is a component being reflected on the
colorant material particles, and the surface reflection light
component is a component being reflected on a surface of the
colorant material layer; and a specular reflection light amount
calculating section for calculating out a specular reflection light
amount of the sample in the other geometry from the components in
the other geometry which are thus calculated out by the lower layer
reflection light component creating section and the upper layer
reflection light component creating section, and the control
program causing a computer to function as each of the sections.
Description
[0001] This Nonprovisional application claims priority under 35
U.S.C. .sctn. 119(a) on Patent Applications Nos. 316933/2004 and
210525/2005 filed in Japan respectively on Oct. 29, 2004, and Jul.
20, 2005, the entire contents of which are hereby incorporated by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a specular gloss simulation
device, a specular gloss simulation method, a control program for
the specular gloss simulation device and storage medium thereof.
The specular gloss simulation method is for simulating a specular
gloss of an image formed by a printing method such as an
electrophotographic printing method, an inkjet printing method, an
offset printing method, or a letterpress printing method.
BACKGROUND OF THE INVENTION
[0003] Gloss is one quality evaluation item of an image sample
produced by various techniques. In general, the gloss depends
largely upon geometry (that is a positional relationship of a light
source, a sample (hereinafter, the image sample is denoted simply
as sample) and a light receiver) under which observation is carried
out. The larger a zenith angle 1 in a light source incidence
direction (in which the light comes from the light source) and a
zenith angle 2 in a light reflection direction (in which the light
goes to the light receiver) as illustrated in FIG. 2, the stronger
the gloss that a person feels. In order to evaluate this gloss
quantitatively as glossiness, presently a glossimeter adopts some
limited kinds of arrangements (JIS Z 8741) such as a combination of
a zenith angle 45.degree. in the direction, in which the light
enters toward a sample 3 and a zenith angle 60.degree. in the light
reflection direction. This arrangement is standardized in, for
example JIS (Japanese Industrial Standards), and the like.
[0004] However, this technique gives glossiness that can be merely
a kind of standardized measure, but can not provide quantitative
data enough for evaluating a property of deviation reflection. In
order to solve this problem, a gonio-spectro photometer system
(gonio-photo spectrometer) and the like, which is generally used in
painting industry, is used. This makes it possible to obtain
quantitative data of the property of deviation reflection. However,
the quantitative measurement using this gonio-spectro photometer
system of an angle of deviation takes very long to obtain the
measurement and can handle only limited varieties of shapes of a
sample. Accordingly, this measurement is not so suitable for
practical use.
[0005] In recent years, in a field of remote sensing, BRDF
(Bidirectional Reflectance Distribution Function) is draws
attention. This is devised based on Shafter's Dichromatic
Reflection Model (refer to Document 1). In the Dichromatic
Reflection Model, as illustrated in FIG. 3, reflection light from a
surface of an object is made of two components called (i) a surface
reflection (light component reflected on a surface) 4 and (ii) an
internal reflection (light component reflected inside) 5. The
surface reflection 4 is a light beam reflected on a surface of the
sample 3 due to a difference in refractive indexes of the sample 3
and the air and has color of a light source 6. The light that
enters inside the sample 3 is repeatedly refracted, absorbed, and
scattered among dye particles 3A, whereby the light is absorbed
into the dye particles 3A depending on the wavelength. Accordingly,
the internal reflection light 5, which is a reflection from the
sample 3, has a color of the sample 3. Various proposed models of
the BRDF are used according to respective purposes.
[0006] Document 2 discloses a method for evaluating a property of
deviation inside reflection. This method simulates an amount of
specular reflection light, by using BRDF. With this method, it is
also possible to simulate glossiness in geometry other than
existing geometry.
[0007] However, in the above method, the amount of the specular
reflection light received by a glossimeter is examined only by the
surface reflection in the Dichromatic Reflection Model and the
specular glossiness is calculated by the BRDF. In an image made of
a concentrated colorant material and thus producing high gloss, it
is possible to ignore the internal reflection light component in
the Dichromatic Reflection Model and a reflection light component
from a base material positioned under a colorant material layer.
However, in a case of an image whose color density from a colorant
material is low, the reflection light component of an lower layer
cannot be ignored. Moreover, in case of a low gloss image, the
internal reflection light component cannot be ignored. Therefore, a
correct value cannot be calculated with the above method.
(Document 1)
COLOR Research and application, Vol. 10, No. 4, pp. 210-218,
1985
(Document 2)
Japanese Unexamined Patent Publication 2003-329586 (published on
Nov. 19, 2003)
SUMMARY OF THE INVENTION
[0008] The present invention is accomplished in view of the
aforementioned problems, and an object of the present invention is
to realize a specular gloss simulation device and a specular gloss
simulation method which can accurately simulate, by using a
Bidirectional Reflectance Distribution Function model, specular
glossiness of an image even if the image has a low density or low
glossiness.
[0009] In order to attain the object, a specular gloss simulation
device according to the present invention for simulating specular
gloss by measuring, in a given geometry, luminance of a sample that
has a base material and a colorant material layer formed on the
base material, and then simulating a specular reflection light
amount in an other geometry from the thus measured luminance, is
provided with: a lower layer reflection light component creating
section for calculating a lower layer reflection light component
from base material luminance, where the base material luminance is
luminance of only the base material measured in a plurality of
geometries, and the lower layer reflection light component is a
component being reflected on the base material and transmitting
through and out of the colorant material layer; an internal
reflection light component creating section for measuring luminance
of the sample in the given geometry, and for creating an internal
reflection light component from the measured luminance and the
lower layer reflection light component, where the internal
reflection light component is a component being reflected from an
interior of the colorant material layer; a surface reflection light
component creating section for measuring luminance of the sample in
the given geometry, and for creating a surface reflection light
component from the measured luminance, the lower layer reflection
light component, and the internal reflection light component, where
the surface reflection light component is a component being
reflected on a surface of the colorant material layer; and a
specular reflection light amount calculating section for obtaining
a specular reflection light amount of the sample from the
components thus created by the lower layer reflection light
component creating section, internal reflection light component
creating section, and surface reflection light component creating
section.
[0010] Moreover, in order to attain the object, another specular
gloss simulation device according to the present invention for
simulating specular gloss by measuring, in a given geometry,
luminance of a sample that has a base material and a colorant
material layer formed on the base material, and then simulating a
specular reflection light amount in an other geometry from the thus
measured luminance, is provided with: a lower layer reflection
light component creating section for calculating a lower layer
reflection light component from base material luminance, where the
base material luminance is luminance of only the base material
measured in a plurality of geometries, and the lower layer
reflection light component is a component being reflected on the
base material and transmitting through and out of the colorant
material layer; an internal reflection light component creating
section for creating an internal reflection light component from
luminance of the sample and the lower layer reflection light
component, where the internal reflection light component is a
component being reflected from an interior of the colorant material
layer, and the luminance of the sample is measured in the given
geometry; a surface reflection light component creating section for
creating a surface reflection light component from the luminance of
the sample, the lower layer reflection light component, and the
internal reflection light component, where the surface reflection
light component is a component being reflected on a surface of the
colorant material layer, and the luminance of the sample is
measured in the given geometry; and a specular reflection light
amount calculating section for obtaining a specular reflection
light amount of the sample from the components thus created by the
lower layer reflection light component creating section, internal
reflection light component creating section, and surface reflection
light component creating section.
[0011] With the above arrangement, the simulation of the specular
gloss is carried out by obtaining the specular reflection light
amount of the sample by more effectively using the Bidirectional
Reflectance Distribution Function model, taking the lower layer
reflection light component and the internal reflection light
component, as well as the surface reflection light component, into
consideration. This makes it possible to calculate out the specular
gloss with high accuracy for low-density image sample and low-gloss
image sample for which accurate calculation of the specular gloss
cannot be done with the conventional art.
[0012] In order to attain the object, still another specular gloss
simulation device according to the present invention for simulating
specular gloss by measuring, in a given geometry, luminance of a
sample that has a base material and a colorant material layer which
is formed on the base material and contains colorant material
particles, and then simulating a specular reflection light amount
in an other geometry from the thus measured luminance, is provided
with: a lower layer reflection light component creating section for
calculating lower layer reflection light components in the given
geometry and the other geometry from base material luminance, where
the base material luminance is luminance of only the base material
measured in a plurality of geometries, and the lower layer
reflection light component is a component being reflected on the
base material and transmitting through and out of the colorant
material layer; an upper layer reflection light component creating
section for calculating a diffuse reflection light component, a
colorant material particle reflection light component, and a
surface reflection light component in the other geometry from the
luminance of the sample measured in the given geometry and the
lower layer reflection light component in the given geometry, the
lower layer reflection light component being calculated out by the
lower layer reflection light component creating section, where the
diffuse reflection light component is a component being diffused
among the colorant material particles contained in the colorant
material layer and transmitting out of the colorant material layer,
the colorant material particle reflection light component is a
component being reflected on the colorant material particles, and
the surface reflection light component is a component being
reflected on a surface of the colorant material layer; and a
specular reflection light amount calculating section for
calculating out a specular reflection light amount of the sample in
the other geometry from the components in the other geometry which
are thus calculated out by the lower layer reflection light
component creating section and the upper layer reflection light
component creating section. With the above arrangement, the
simulation of the specular gloss is carried out by obtaining the
specular reflection light amount of the sample by effectively using
the Bidirectional Reflectance Distribution Function model, taking
the lower layer reflection light component of the base material and
the diffuse reflection light component and colorant material
particle reflection light component of the colorant material layer,
as well as the surface reflection light component of the colorant
material layer, into consideration. This makes it possible to
calculate out the specular gloss with high accuracy for low-density
image sample and low-gloss image sample for which accurate
calculation of the specular gloss cannot be done with the
conventional art.
[0013] In order to attain the object, a specular gloss simulation
method according to the present invention for simulating specular
gloss by simulating a specular reflection light amount of a sample
having a base material and a colorant material layer formed on the
base material, is arranged to include: (i) creating a lower layer
reflection light component by calculating out the lower layer
reflection light component from base material luminance where the
base material luminance is luminance of only the base material
measured in a plurality of geometries which are varied in incident
light angle and reflection light angle by a constant angle, the
lower layer reflection light component is a component being
reflected on the base material and transmitting through and out of
the colorant material layer; (ii) creating an internal refection
light component by simulating, by using a Bidirectional Reflectance
Distribution Function model, the internal refection light component
in the other geometry from an internal reflection light component
calculated out from luminance of the sample measured in one
non-specular reflection geometry and the lower layer reflection
light component, where the internal reflection light component is a
component being reflected from an interior of the colorant material
layer; (iii) creating a surface reflection light component by
simulating, by using a Bidirectional Reflectance Distribution
Function model, the surface reflection light component in the other
geometry from a surface reflection light component calculated out
from luminance of the sample measured in one non-specular
reflection geometry, the lower layer reflection light component,
and the internal reflection light component, where the surface
reflection light component is a component being reflected on a
surface of the colorant material layer; and (iv) calculating out a
specular reflection light amount of the sample from the lower layer
reflection light component, internal reflection light component,
and surface reflection light component thus obtained.
[0014] The specular gloss simulation device of the present
invention is used for simulating, by using the Bidirectional
Reflectance Distribution Function model, a specular reflection
light amount of a sample in each geometry, the sample having, as a
sample image, the colorant material layer on the base material,
where the base material may be paper, an OHP film or the like, and
the colorant material layer contains toner, pigment ink, dye ink or
the like. From the thus simulated specular reflection light amount,
the specular gloss of the sample is simulated in the method
according to the present invention.
[0015] With the above arrangement, the simulation of the specular
gloss is carried out by obtaining the specular reflection light
amount of the sample by effectively using the Bidirectional
Reflectance Distribution Function model, taking the lower layer
reflection light component and the internal reflection light
component, as well as the surface reflection light component, into
consideration. This makes it possible to calculate out the specular
gloss with high accuracy for low-density image sample and low-gloss
image sample for which accurate calculation of the specular gloss
cannot be done with the conventional art.
[0016] In order to attain the object, a specular gloss simulation
method according to the present invention for simulating specular
gloss by simulating a specular reflection light amount of a sample
having a base material and a colorant material layer which is
formed on the base material and contains colorant material
particles, is arranged to include: (i) creating lower layer
reflection light components in the given geometry and the other
geometry by calculating out the lower layer reflection light
components from base material luminance where the base material
luminance is luminance of only the base material measured in a
plurality of geometries, the lower layer reflection light component
is a component being reflected on the base material and
transmitting through and out of the colorant material layer; (ii)
calculating out a diffuse reflection light component, a colorant
material particle reflection light component, and a surface
reflection light component from the luminance of the sample
measured in the given geometry and the lower layer reflection light
component in the given geometry, the lower layer reflection light
component being calculated out in the step (i), where the diffuse
reflection light component is a component being diffused among the
colorant material particles contained in the colorant material
layer and transmitting out of the colorant material layer, the
colorant material particle reflection light component is a
component being reflected on the colorant material particles, and
the surface reflection light component is a component being
reflected on a surface of the colorant material layer; and (iii)
calculating out a specular reflection light amount of the sample in
the other geometry from the diffuse reflection light component, the
lower layer reflection light component in the other geometry, which
is thus calculated in the step (i) and the colorant material
particle reflection light component, and the surface reflection
light component thus calculated in the step (ii).
[0017] With the above arrangement, the simulation of the specular
gloss is carried out by obtaining the specular reflection light
amount of the sample by effectively using the Bidirectional
Reflectance Distribution Function model, taking the lower layer
reflection light component of the base material and the diffuse
reflection light component and colorant material particle
reflection light component of the colorant material layer, as well
as the surface reflection light component of the colorant material
layer, into consideration. This makes it possible to calculate out
the specular gloss with high accuracy for low-density image sample
and low-gloss image sample for which accurate calculation of the
specular gloss cannot be done with the conventional art.
[0018] For a fuller understanding of the nature and advantages of
the invention, reference should be made to the ensuing detailed
description taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a block diagram of an arrangement of a specular
gloss simulation device, according to an embodiment 1 of the
present invention.
[0020] FIG. 2 is a diagram schematically illustrating specular
reflection geometry.
[0021] FIG. 3 is an explanatory diagram schematically illustrating
a Dichromatic Reflection Model.
[0022] FIG. 4 is a diagram schematically illustrating a method of
dividing reflection light components of a sample having a structure
with two layers, according to the embodiment 1.
[0023] FIG. 5 is a diagram schematically illustrating a geometric
arrangement in a BRDF model.
[0024] FIG. 6 is a diagram schematically illustrating a geometric
definition of a surface of a material in the BRDF model.
[0025] FIG. 7 is a diagram schematically illustrating a refraction
phenomenon of light and attenuation of an amount of light, which
are taken into consideration when an lower layer reflection light
component is calculated in the embodiment 1.
[0026] FIG. 8 is a flow chart of a process for calculating a
specular reflection light component in each geometry from a
measured value of luminance in a predetermined geometry in the
embodiment 1.
[0027] FIG. 9 is a diagram schematically illustrating an example of
a data input screen displayed on a display section of the specular
glossiness simulation device as illustrated in FIG. 1.
[0028] FIG. 10 is a diagram schematically illustrating another
example of a data input screen displayed on a display section of
the specular glossiness simulation device as illustrated in FIG.
1.
[0029] FIG. 11 is a diagram schematically illustrating an example
of a screen displaying a result of a measurement, the result being
displayed on a display section of the specular glossiness
simulation device as illustrated in FIG. 1.
[0030] FIG. 12 is a block diagram of an arrangement of a computer
system including a function of the specular glossiness simulation
device as illustrated in FIG. 1.
[0031] FIG. 13 is a flow chart of a process for calculating a
specular reflection light component in each specular reflection
geometry from a measured value of luminance in a predetermined
geometry in an embodiment 2.
[0032] FIG. 14 is a diagram schematically illustrating a method of
dividing reflection light components of a sample having a structure
with two layers, according to the embodiment 2.
[0033] FIG. 15 is a diagram schematically illustrating a refraction
phenomenon of light and attenuation of an amount of light, which
are taken into consideration when an lower layer reflection light
component is calculated in the embodiment 2.
[0034] FIG. 16 is a block diagram of an arrangement of a specular
gloss simulation device, according to the embodiment 2 of the
present invention.
[0035] FIG. 17 is a diagram schematically illustrating an example
of a data input screen displayed on a display section of the
specular glossiness simulation device as illustrated in FIG.
16.
[0036] FIG. 18 is a diagram schematically illustrating another
example of a data input screen displayed on a display section of
the specular glossiness simulation device as illustrated in FIG.
16.
[0037] FIG. 19 is a diagram schematically illustrating an example
of a screen displaying a result of a measurement, the result being
displayed on a display section of the specular glossiness
simulation device as illustrated in FIG. 16.
[0038] FIG. 20 (a) is a graph illustrating a result of an example 1
(specular glossiness simulation by using a high-concentration toner
sample), and FIG. 20(b) is a graph illustrating a result of an
example 2 (specular glossiness simulation by using a toner sample
having low concentration).
[0039] FIGS. 21(a) and 21(b) are graphs illustrating results of an
example 3.
[0040] FIG. 22(a) is a graph illustrating a result of an example 4
(specular glossiness simulation by using a high-concentration toner
sample), and FIG. 22(b) is a graph illustrating a result of an
example 5 (specular glossiness simulation by using a toner sample
having low concentration).
[0041] FIG. 23(a) and FIG. 23(b) are graphs illustrating results of
an example 6.
[0042] FIG. 24 is a flow chart of a process for calculating a
specular reflection light component in each geometry from a
measured value of luminance in a predetermined geometry in the
embodiment 3.
[0043] FIG. 25 is a block chart of an arrangement of a specular
gloss simulation device, according to the embodiment 3 of the
present invention.
[0044] FIG. 26 is a diagram schematically illustrating an example
of a data input screen displayed on a display section of the
specular glossiness simulation device as illustrated in FIG.
25.
[0045] FIG. 27 is a diagram schematically illustrating another
example of a data input screen displayed on a display section of
the specular glossiness simulation device as illustrated in FIG.
25.
[0046] FIG. 28 is a diagram schematically illustrating an example
of a screen displaying a result of a measurement, the result being
displayed on a display section of the specular glossiness
simulation device as illustrated in FIG. 25.
[0047] FIG. 29(a) is a graph illustrating a result of an example 7
(specular glossiness simulation by using a highly concentrated
toner sample), and FIG. 29(b) is a graph illustrating a result of
an example 8 (specular glossiness simulation by using a toner
sample having low concentration).
[0048] FIG. 30(a) and FIG. 30(b) are graphs illustrating results of
an example 9.
DESCRIPTION OF THE EMBODIMENTS
First Embodiment
[0049] Referring to FIG. 1 through FIG. 12, the following will
describe one embodiment of the present invention. In the present
embodiment, a specular gloss simulation device is described in
which specular gloss is simulated by measuring luminance of a
sample in a given geometry (having predetermined incident light
angle and reflection light angle, and then a specular reflection
light amount is simulated in a different geometry from the thus
measured luminance, the sample including paper (base material) and
a toner image (colorant material layer) formed on the paper
according to an electrophotographic method. In the present
embodiment, one of the specular reflection geometries and one of
the non-specular reflection geometries are selected as the given
geometries, and gonio data of these given geometries are
measured.
[0050] First, the specular gloss simulation device of the present
embodiment is described in regard to the dichromatic reflection
(BRDF) model theory for the simulation of specular gloss of a
sample. Here, description of the BRDF model will be given through
the case where it is used to calculate reflection light components
of the sample having the bilayer structure in which a colorant
material layer is formed on a base material.
[0051] FIG. 4 schematically illustrates how the reflection light
components of the bilayer sample are split into individual
components. As illustrated in FIG. 4, a sample 3 includes an upper
layer portion 13 made of a toner image (colorant material layer),
and a lower layer portion 12 made of a base material such as paper
or a transparent film. According to the dichromatic reflection
(BRDF) model theory, the reflection light components of the light
from a light source 6 include a surface reflection light component
(Lrs) 7 and an internal reflection light component (Lri) 8, both
from the upper layer portion 13, and a surface reflection light
component 9 and an internal reflection light component 10, both
from the lower layer portion 12. The composite light of these
components becomes the reflected light from the sample 3. In order
to calculate the reflected light components 7 through 10 according
to the BRDF model, more than one unmeasurable parameter needs to be
estimated.
[0052] However, since the measurement of the internal reflection
light component 10 reflected from the lower layer portion 12 is
difficult, the present invention combines the internal reflection
light component 10 with the surface reflection light component 9
also from the lower layer portion 12, and uses the sum of these
reflection light components as a lower layer reflection light
component (Lru) 11. By calculating the lower layer reflection light
component 11 based on measurement data obtained only from the lower
layer portion 12, a specular reflection light amount can be
accurately calculated for a wide variety of samples images
according to the BRDF model. By thus calculating the lower layer
reflection light component 11 with the surface reflection light
component 7 and internal reflection light component 8 from the
upper layer portion 13, an accurate specular reflection light
amount can be obtained.
[0053] As the mathematical models effective for calculating the
respective reflection light components, the present invention can
use the following BRDF models (1) through (4).
(1) Ward Model
[0054] Reference: Ward G. J., Measuring and modeling anisotropic
reflection, Computer Graphics Vol. 26, No. 2, pp. 265-272,
1992.
(2) Phong Model
[0055] Reference: B. Phong, Illumination for computer-generated
pictures, Communications of the ACM, Vol. 18, No. 6, pp. 311-317,
1975.
(3) Oren-Nayar Model
Reference: Michael Oren and Shree K. Nayar, Generalization of the
Lambertian Model and Implications for Machine Vision, International
Journal of Computer Vision, Vol. 14, pp. 227-251, 1995.
(4) Torrance-Sparrow Model
[0056] Reference: K. E. Torrance and E. M. Sparrow, Theory for
Off-Specular Reflection From Roughened Surfaces, J. Opt. Soc. Am.
Vol. 57, No. 9, pp. 1105-1114, 1967.
[0057] Of these mathematical models, the Ward model and the Phong
model have been proposed based on isotropic scattering of light,
whereas the Oren-Nayar model and the Torrance-Sparrow model are
based on non-isotropic scattering of light. In the present
embodiment, the Torrance-Sparrow model is adopted as the
mathematical model for calculating the surface reflection light
component 7, and the Oren-Nayar model is adopted as the
mathematical model for calculating the internal reflection light
component 8. This is because more accurate values can be obtained
when non-isotropic scattering of light is taken into consideration,
though it involves complex equations.
[0058] FIG. 5 represents a geometric arrangement according to the
BRDF model. FIG. 6 represents geometric definitions of object
surfaces according to the BRDF model. While FIG. 2 only represents
a specular reflection geometry (.theta.i=.theta.r,
oi+or=180.degree. in FIG. 5), FIG. 5 represents a three dimensional
multi-angle geometry with the xyz axes (common geometry including
the specular reflection geometry). FIG. 6 represents an
approximation model that has been proposed for sample surfaces in
the modeling of non-isotropic scattering of light according to the
Oren-Nayar model and the Torrance-Sparrow model. It is assumed here
that the sample has a non-planer surfaces with microscopic
irregularities (roughness) made up with facets. Here, steric effect
and steric hindrance due to an aggregation of such facets are taken
into consideration when the reflection luminance is expressed.
[0059] In calculating the internal reflection light component Lri
using the Oren-Nayar model, mathematical value LrON is calculated
first according to Equation (1) below. LrON = .sigma. .pi. .times.
E0 .times. .times. cos .times. .times. .theta.I [ C1 .function. (
.sigma. ) + cos .function. ( .PHI. .times. .times. r - .PHI.I )
.times. C2 .function. ( .alpha. ; .beta. ; .PHI. .times. .times. r
- .PHI.I ; .sigma. ) .times. tan .times. .times. .beta. ) + ( 1 -
cos .function. ( .PHI. .times. .times. r - .PHI.I ) ) .times. C3
.function. ( .alpha. ; .beta. ; .sigma. ) .times. tan .function. (
.alpha. + .beta. 2 ) + 0.17 .times. .rho. 2 .pi. .times. E0 .times.
.times. cos .times. .times. .theta.I .times. .times. .sigma. 2
.sigma. 2 + 0.13 .function. [ 1 - cos .function. ( .PHI. .times.
.times. r - .PHI.I ) .times. ( 2 .times. .beta. .pi. ) 2 ] .times.
.times. C1 = 1 - 0.5 .times. .times. .sigma. 2 .sigma. 2 + 0.33
.times. .times. C2 = { 0.45 .times. .times. .sigma. 2 .sigma. 2 +
0.09 .times. sin .times. .times. .alpha. ( if .times. .times. cos
.function. ( .PHI. .times. .times. r - .PHI.I ) .gtoreq. 0 ) 0.45
.times. .times. .sigma. 2 .sigma. 2 + 0.09 .times. sin .times.
.times. .alpha. ( sin .times. .times. .alpha. - ( 2 .times. .beta.
.pi. ) 3 ) .times. .times. ( if .times. .times. not ) .times.
.times. C3 = 0.125 .times. ( .sigma. 2 .sigma. 2 + 0.09 ) .times. (
4 .times. .alpha..beta. .pi. 2 ) 2 ( 1 ) ##EQU1##
[0060] In Equation (1), .theta.i is the zenith angle in the light
source direction, oi is the azimuth angle in the light source
direction, .theta.r is the zenith angle in the light reflection
direction, or is the azimuth angle in the light reflection
direction, .sigma. is the roughness variable of the surface
profile, E0 is the radiant luminance incident on the sample, .rho.
is the refractive index of the microscopic surface of the sample
surface, .alpha.=max [.theta.r, .theta.i], and .beta.=min
[.theta.r, .theta.i] (see FIG. 5, FIG. 6).
[0061] In calculating the surface reflection light component Lrs
according to the Torrance-Sparrow model, mathematical value LrTS is
calculated first according to Equation (2) below. LrTS = E0 .times.
.times. FGAF cos .times. .times. .theta. .times. .times. r .times.
.times. cos .times. .times. .theta. .times. .times. a .times. c
.times. .times. e - .theta. .times. .times. a 2 2 .times. .sigma. 2
.times. .times. GAF = max .function. [ 0 , Min .function. [ 1 , 2
< s , n > < a , n > < s , a > , 2 < v , n >
< a , n > < v , a > ] ] .times. .times. c = .intg.
.theta. .times. .times. a = 0 .pi. 2 .times. .intg. .PHI. .times.
.times. a = 0 2 .times. .pi. .times. e - .theta. .times. .times. a
2 2 .times. .sigma. 2 .times. sin .times. .times. .theta. .times.
.times. a .times. d .PHI. .times. .times. a .times. .times. d
.theta. .times. .times. a ( 2 ) ##EQU2##
[0062] In Equation (2), F is the Fresnel reflection index, n is the
normal vector of the sample 3, s is the vector of the light source
direction, v is the vector of the light reflection direction, a is
the bisector vector of s and v, .theta.r is the zenith angle of the
light reflection direction, .theta.a is the zenith angle of vector
a, oa is the azimuth angle of vector a, .sigma. is the roughness
variable of the surface profile, and E0 is the radiant luminance
incident on the sample. Further, in Equation (2), <x, y> (x,
y are arbitrary numbers) is the inner products of the vectors (see
FIG. 5, FIG. 6).
[0063] Now, referring to the flow chart in FIG. 8, a method will be
described by which the amount of specular reflection light is
calculated for each geometry from a measured value of luminance in
a predetermined geometry using the above technique.
[0064] First, to calculate an lower layer reflection light
component Lru, the transmittance of only the upper layer portion
(toner image) 13 of a sample for which the specular reflection
light component is to be calculated is calculated (step S1). The
measurement geometry here includes a light source, a sample, and a
light receiver positioned along a straight line. In such a
geometry, the light source shines right above the sample. That
light which is received by the light receiver located right under
the sample is measured with a transmission density meter as light
having transmitted the sample. Then, the transmission density Dt
for only the upper layer portion 13 is obtained by calculating a
differential between a sample with a toner image formed thereon (a
sample made up of the upper layer portion 13 and the lower layer
portion 12) and a sample made up of only the lower layer portion
(paper) 12. A transmittance Tt for only the upper layer portion 13
(in other words, the toner image) is given by Tt=10 (-Dt).
[0065] Throughout the following steps, the refractive index
(literature value) of resin which is a main component of toner is
used as the refractive index of the upper layer portion (toner
image) 13. With current measuring theory, it is impossible to
measure the refractive index of a toner layer on paper. This is why
the refractive index of the upper layer portion 13 is not measured,
and the refractive index (literature value) of resin which is a
main component of the toner is used instead, in the present
embodiment. Actual measurement would yield a substantially
identical value.
[0066] Next, a sample with no upper layer portion 13, that is, a
sample with only the lower layer portion 12 (in the present
embodiment, paper or transparent film still carrying no toner image
formed thereon) is prepared. With the light source incidence
direction and the light reflection direction of the sample with
only the lower layer portion 12 being resolved at high resolution,
gonio data is then measured (step S2). The "Gonio data" indicates
angle dependence of the luminance of scattered light from a sample
which is measured with a gonio-spectro photometer. Here, CIE 1976
L*a*b* (CIE: Commission International de l'Eclairage. L* is a
lightness, and a* indicates redness-greenness and b* indicates
yellowness-blueness) color space is used for the measurement.
Therefore, the value of L* is employed as the gonio data.
[0067] The lower layer reflection light component Lru is calculated
from this data (step S3). FIG. 7 is a diagram schematically
illustrating a refraction phenomenon of light and attenuation of an
amount of light, which are taken into consideration when the lower
layer reflection light component Lru is calculated. Light incident
to the sample at an incident light angle .theta.i refracts at the
interface between an air layer 15 and the upper layer portion 13.
This refraction phenomenon obeys Fresnel's theory. The angle
.theta.t after the refraction is given by Fresnel's law
(n1.times.sin .theta.i=n2.times.sin .theta.t, where n1 is the
refractive index of a pre-incidence medium, and n2 the refractive
index of a post-incidence medium). Light is attenuated at the
interface due to the refraction as it passes through the toner
layer. The Fresnel transmittance Tn of that light is given by
equation (3): Tn = [ ( n2 .times. .times. cos .times. .times.
.theta. .times. .times. t n1 .times. .times. cos .times. .times.
.theta.I ) .times. ( 2 .times. n1 .times. .times. cos .times.
.times. .theta.I n2 .times. .times. cos .times. .times. .theta.I +
n1 .times. .times. cos .times. .times. .theta. .times. .times. t )
2 + ( n2 .times. .times. cos .times. .times. .theta. .times.
.times. t n1 .times. .times. cos .times. .times. .theta.I ) .times.
( 2 .times. n1 .times. .times. cos .times. .times. .theta.I n1
.times. .times. cos .times. .times. .theta.I + n2 .times. .times.
cos .times. .times. .theta. .times. .times. t ) 2 ] / 2 ( 3 )
##EQU3##
[0068] As light passes through the upper layer portion 13, the
light is attenuated by the upper layer portion 13 before reaching
the lower layer portion 12. The attenuation obeys the Beer-Lambert
law (-logT=a.times.d, where a is the absorption coefficient of a
colorant material layer, d is the thickness of the colorant
material layer, and T is the transmittance). The length of the
optical path in the upper layer portion 13 traveled by the light
before reaching the lower layer portion 12 changes with the
incident light angle. The apparent transmittance Tt' in accordance
with the changes in the length of the optical path is given by
-logTt'=a.times.(d/cos .theta.i). Light attenuation is evaluated in
terms of the apparent transmittance.
[0069] From the above description, the amount of incident light
reaching the lower layer portion 12 is calculated by evaluating the
attenuation of the amount of light from the apparent transmittance
Tt' in accordance with the Fresnel transmittance Tn and the changes
in the length of the optical path. The calculation also takes into
consideration the changes of the incident light angle of the light
to the lower layer portion 12 caused by the refraction. A similar
optical phenomenon occurs when the reflection from the lower layer
portion 12 travels back to the air layer. Therefore, the lower
layer reflection light component Lru is calculated by calculating
from the gonio data of the sample with only the lower layer portion
(paper) measured in S2 for all incident light angles and light
reflection angles with the two refractions and an attenuation of
light (see FIG. 7) taken into consideration. If the incident light
angle .theta.t after the refraction has decimal places, the angle
is interpolated by proration from the preceding and succeeding
angle values. There are no particular limitations on angle
resolution in the process. Here, the resolution is 1.degree.
because the measuring device has a maximum angle resolution of
1.degree.. To calculate the specular reflection light component
more precisely, the angle resolution is preferably 1.degree. or
less.
[0070] As described in the foregoing, the incident direction of
light to the upper layer portion is obtained from the refractive
index. In addition, since the light is absorbed and attenuated by
the upper layer portion, the degree of attenuation is evaluated
from a transmittance. In other words, from the refractive indexes
are calculated the optical path involving the refractions at the
air layer and the upper layer portion and the subsequent incidence
and the optical path involving the reflection from the lower layer
portion (paper) and the further refractions at the upper layer
portion and the air layer. The attenuation of the light is
evaluated from the transmittance in accordance with these optical
paths. This value is subjected to a computation (multiplied by the
gonio data of the sample with only the lower layer portion (paper))
to obtain the lower layer reflection light component Lru.
[0071] Next, to calculate the internal reflection light component
Lri, the luminance value Lra (L* of CIE 1976 L*a*b*) of the sample
is measured in one certain geometry which contains almost zero
surface reflection light component (step S4). This geometry is
termed the non-specular reflection geometry. Generally, the more
the geometry differs from specular reflection, the smaller the
surface reflection light component. The non-specular reflection
geometry selected here therefore preferably has a large light
source incident light angle and includes a light source incidence
position and a light receiving position in close proximity.
[0072] For the present embodiment, an exemplary geometry is
selected where the light source incident light angle .theta.i is
45.degree. (.phi.i=0.degree.) and the light reflection angle
.theta.r is -60.degree. (.phi.r=0.degree.). The lower layer
reflection light component Lru calculated in the same geometry is
subtracted from the luminance value Lra measured in the geometry.
Further, the surface reflection light component Lrs is approximated
to 0. The remaining reflection light component is designated the
internal reflection light component Lri. The internal reflection
light component Lri thus obtained is subjected to fitting using an
Oren-Nayar model (step S5). Fitting here means that an unknown
parameter is calculated, and the internal reflection light
component is obtained for each geometry, so that the internal
reflection light component calculated from the luminance value Lra
measured in the selected non-specular reflection geometry can be
represented with an Oren-Nayar model.
[0073] The roughness variable .sigma. (see FIG. 5) indicating the
roughness of the surface used in the above process is a parameter
defining the range of the reflection light component in the
physical model. The variable is virtually meaningless and therefore
fixed (for example, at 1 or 0.5) in the present case. E0 (see FIG.
5) is irradiance incident to the sample. Here, since the measured
value space is CIE 1976 L*a*b* space, and L* is employed,
E0=100.pi.. From these values, the reflectance .rho. of a small
plane on the sample surface is estimated. The reflectance .rho. of
the small plane on the sample surface is never negative in the
physical model; only positive values are employed.
[0074] Inserting these numeric values to equation (1), the
parameters required by the Oren-Nayar model are estimated. Thus, an
Oren-Nayar model calculated value LrON is determined. The magnitude
of the Oren-Nayar model calculated value LrON is also subjected to
fitting by estimating the reflectance parameter .rho. for the small
plane on the sample surface. It is therefore possible to calculate
the internal reflection light component Lri for each geometry
without any particular scaling of the Oren-Nayar model calculated
value LrON. That is, the calculated LrON corresponds to the
internal reflection light component Lri (Lri=LrON).
[0075] Finally, to calculate the surface reflection light component
Lrs, the luminance value Lrb in one specular reflection geometry is
measured (step S6). The geometry is termed the specular reflection
geometry. The specular reflection geometry selected here is such
that the light source incident light angle is 45.degree.
(.phi.i=0.degree.), and the light reflection angle is 45.degree.
(.phi.r=180.degree.). Note that the present invention is not
limited to these angles. The lower layer reflection light component
Lru calculated in the same geometry and the internal reflection
light component Lri are subtracted from the luminance value Lrb (L*
of CIE 1976 L*a*b*) measured in this geometry. The remaining
reflection light component is designated the surface reflection
light component Lrs. The surface reflection light component Lrs
thus obtained is subjected to fitting using a Torrance-Sparrow
model (step S7). Fitting here means obtaining, by using a
Torrance-Sparrow model, the surface reflection light component and
the colorant material particle reflection light component in each
specular reflection geometry from the surface reflection light
component calculated from the luminance value Lrb measured in the
selected specular reflection geometry and the colorant material
particle reflection light component. The Torrance-Sparrow model
involves no estimation parameters. Inputting request parameters
determines a Torrance-Sparrow model calculated value LrTS.
[0076] However, the surface reflection light component Lrs (=Lrb)
cannot be expressed by the Torrance-Sparrow model calculated value
LrTS itself. The Torrance-Sparrow model calculated value LrTS needs
be scaled. Accordingly, the value of a shape parameter k that
satisfies Lrs=Lrb=k.times.LrTS is calculated, and the magnitude of
the Torrance-Sparrow model calculated value LrTS capable of
reproducing the surface reflection light component Lrs is
regulated. In the process, F is set to 1 to obtain surface
reflection in the specular reflection geometry. The surface
reflection light component Lrs for each specular reflection
geometry is calculated as described above.
[0077] With these steps, the lower layer reflection light component
Lru, the internal reflection light component Lri, and the surface
reflection light component Lrs are individually calculated. By
adding these calculated values in the same specular reflection
geometry, the specular reflection light component (amount of
specular reflection light) Lr is obtained (step S8).
[0078] In the aforementioned specular gloss simulation method, S1
to S3 are lower layer reflection light component forming steps, S4
to S5 are internal reflection light component forming steps, S6 to
S7 are surface reflection light component forming steps, and S8 is
a specular reflection light amount calculating step.
[0079] Next, an arrangement of a specular gloss simulation device
according to the present invention is described below. The specular
gloss simulation device according to the present embodiment
calculates out the specular reflection light component of each
specular reflection geometry by performing the process illustrated
in the flowchart of FIG. 8. From the specular reflection light
components thus obtained, the specular gloss simulation device
simulates the specular gloss. In FIG. 1, an arrangement of a
specular gloss simulation device 100 according to the present
invention is illustrated.
[0080] As illustrated in FIG. 1, the specular gloss simulation
device 100 is provided mainly with a calculating section 101, an
operation input section 102, a storage 103, a gonio data measuring
section 104. The calculating section 101 calculates out a specular
reflection light component from (a) data of refractive index and
transmittance (which has been inputted via the operation input
section 102) of the upper layer portion (toner image) 13, (b)
non-specular reflection geometry/specular reflection geometry being
designated via the operation input section 102, and (c) gonio data
being measured by the gonio data measuring section 104.
[0081] The calculating section 101 is provided with a lower layer
reflection light component calculating section (lower layer
reflection light component creating section) 111, an internal
reflection light component creating section 112, a surface
reflection light component creating section 113, and a specular
reflection light component calculating section (specular reflection
light amount calculating section) 114.
[0082] The lower layer reflection light component calculating
section 111 is used for calculating a lower layer reflection light
components (Lru) in each geometry.
[0083] The internal reflection light component creating section is
used for calculating an internal reflection light component (Lri)
from a measured gonio data in one non-specular reflection geometry,
and performing fitting process to fit the thus calculated internal
reflection light component (Lri) to the Oren-Nayar model thereby to
obtain an internal reflection light component (Lri) in each
geometry.
[0084] The surface reflection light component creating section 113
is used for calculating a surface reflection light component (Lrs)
from a measured gonio data in one specular reflection geometry, and
performing fitting process to fit the thus calculated surface
reflection light component (Lrs) to the Torrance-Sparrow model
thereby to obtain a surface reflection light component (Lrs) in
each specular reflection geometry.
[0085] The specular reflection light component calculating section
(specular reflection light amount calculating section) 114 is used
for calculating a specular reflection light component (specular
reflection light amount) (Lr) by adding up the lower layer
reflection light component (Lru), internal reflection light
component (Lri), and surface reflection light component (Lrs) thus
obtained via the respective sections. The specular reflection light
component calculating section 114 adds up the reflection light
components of the same specular reflection geometry thereby to
calculate out the specular reflection light component in each
specular reflection geometry.
[0086] Moreover, the internal reflection light component creating
section 112 is provided with an Lri calculating section 141 for
calculating the internal reflection light component (Lri) from the
measured gonio data in one non-specular reflection geometry, and an
Lri fitting process section 142 for performing fitting process to
fit the thus calculated internal reflection light component (Lri)
to the Oren-Nayar model thereby to obtain the internal reflection
light component in each geometry.
[0087] Moreover, the surface reflection light component creating
section 113 is provided with an Lrs calculating section 131 for
calculating the surface reflection light component (Lrs) from the
measured gonio data in one specular reflection geometry, and an Lrs
fitting process section 132 for performing fitting process to fit
the thus calculated surface reflection light component (Lrs) to the
Torrance-Sparrow mode thereby to obtain the surface reflection
light component (Lrs) in each specular reflection geometry.
[0088] The operation input section 102 is used for inputting
various numerical values necessary for the calculation of the
specular reflection light component, and for displaying a result of
calculation performed by the calculating section 101. The operation
input section 102 includes operation keys 121 for inputting
numerical values and/or the like, and a display section 122 for
displaying items such as information inputted via the operation
keys 121, the result of calculation, and/or the like.
[0089] The storage section 103 is used for storing therein a result
of the measurement performed by the gonio data measuring section
104, and the result of the calculation performed by the calculating
section 101. The storage section 103 is provided with a first
memory 151 (LUT 1) and a second memory 152 (LUT 2). The first
memory 151 is for storing therein gonio data of a sample measured
by the deviation angle measuring section 104, the sample having a
lower layer portion (paper) 12 only. The second memory 152 is for
storing therein each reflection light component calculated out by
the calculating section 101.
[0090] The gonio data measuring section 104 measures gonio data of
the sample having the lower layer portion (paper) 12 only, and
gonio data of a sample having a two-layered structure, that is,
having the lower layer portion 12 and an upper layer portion (toner
image) 13. The gonio data measuring section 104 has an angular
resolution of 1.degree., by which the gonio data measuring section
104 is able to measure the gonio data per degree. For simulating
the specular glossiness by using the specular gloss simulation
device 100, the gonio data of the sample having the lower layer
portion (paper) 12 only is measured per degree, meanwhile for the
sample having the lower layer portion 12 and the upper layer
portion 13, it is only required to measure the gonio data of one
specular reflection geometry and one non-specular reflection
geometry.
[0091] Next, how to simulate the specular gloss in each specular
reflection geometry of a sample by using the specular gloss
simulation device 100 is described below, referring to FIGS. 1 and
8.
[0092] Firstly, transmittance and refractive index of an upper
layer portion of a sample (toner image) are measured (at S1 in FIG.
8). The transmittance and refractive index are to be inputted into
the specular gloss simulation device 100 in order to measure the
specular gloss component. Transmittance Tt is calculated out from
Equation Tt=10 (-Dt), where Dt is a transmission density of only
the upper layer portion. The transmission density is worked out by
obtaining a difference between transmission density of the sample
on which the toner image is formed (i.e., the sample having the
lower layer portion 12 and the upper layer portion 13) and that of
the sample having the lower layer portion (paper) 12 only. A
transmission density meter is used to measure the transmission
density of the sample on which the toner image is formed (i.e., the
sample having the lower layer portion 12 and the upper layer
portion 13) and that of the sample having the lower layer portion
(paper) 12 only.
[0093] The measurement of the transmission density may be carried
out with a X-rite model 820 transmission densitometer made by
X-rite Inc.
[0094] In the following process a refractive index (literature
value) of a resin which is a main component of the toner is used as
the refractive index of the upper layer portion (toner image)
13.
[0095] Next, the transmittance and the refractive index of the
upper layer portion 13 of the sample thus measured by the above
methods are inputted via the operation keys 121 of the operation
input section 102. FIG. 9 illustrates an example of a data input
screen displayed on the display section 122 of the specular gloss
simulation device 100. On the data input screen illustrated in FIG.
9, an input item 20 for the refractive index of the sample to be
measured and an input item 21 for transmittance of the sample to be
measured are displayed. Further, an OK key 22, and a cancel key 23
are displayed on the data input screen illustrated in FIG. 9, which
are touch-panel keys. Via the operation keys 121, the transmittance
and the refractive index thus obtained by the above methods are
inputted respectively into the input items 20 and 21 on the display
section 122. If the cancel key 23 is pressed on this data input
screen, a measurement mode is terminated with the data input screen
inactivated.
[0096] Then, a base material made of the same material as that of
the base material of the sample to be measured (i.e., the sample
having only the lower layer portion) is put in the gonio data
measuring section 104 of the specular gloss simulation device 100,
then the OK key 22 is pressed. In this way, the gonio data
measuring section 104 measures the gonio data (CIE 1976*a*b*L*) of
the sample having only the lower layer portion (at S2 in FIG. 8).
The gonio data thus measured is stored in the first memory 151 of
the storage section 103.
[0097] As the gonio data measuring section 104, gonio-photo
spectrometer GSP-2S (made by Murakami Shikisai) may be used, for
example. Moreover, the gonio data measurement of the sample having
only the lower layer portion has the angular resolution of
1.degree. with respect to the light source incident light angle and
reflection light angle. Therefore, the first memory 151 stores the
gonio data in association with the incident light angle and the
reflection light angle, the gonio data being measured at the
incident light angle and the reflection light angle per degree.
[0098] Next, based on the refractive index theory and attenuation
theory, the lower layer reflection light component calculating
section 111 calculates the lower layer reflection light component
(Lru) in each geometry from the refractive index and transmittance
of the upper layer portion which are inputted via the operation
input section 102, and the gonio data stored in the first memory
151 (at S3 in FIG. 8). The lower layer reflection light component
(Lru) thus calculated is then stored in the second memory 152 in
the storage section 103.
[0099] After that, a similar process is carried out for a given
non-specular reflection geometry selected. Information on the
non-specular reflection geometry is inputted via the operation
input section 102, and then the gonio data in the non-specular
reflection geometry is measured (at S4 in FIG. 8). From the gonio
data thus measured, the internal reflection light component (Lri)
of the non-specular reflection geometry is calculated out. Then,
fitting process carried out in which the internal reflection light
component (Lri) of the non-specular reflection geometry is applied
in the Oren-Nayar model, thereby to obtain the internal reflection
light component (Lri) in each geometry (at S5 in FIG. 8).
[0100] Further, a similar process is carried out for a given
specular reflection geometry selected. Information on the specular
reflection geometry is inputted via the operation input section
102, and then the gonio data in the specular reflection geometry
(at S6 in FIG. 8). From the gonio data thus measured, the surface
reflection light component (Lrs) of the specular reflection
geometry is calculated out. Then, fitting process is carried out in
which the surface reflection light component (Lrs) of the specular
reflection geometry is fitted to the Torrance-Sparrow model,
thereby to obtain the surface reflection light component (Lrs) in
each specular reflection geometry (at S7 in FIG. 8).
[0101] FIG. 10 gives an example of the data input screen displayed
on the display section 122, for the input of the information
regarding the selected non-specular reflection geometry and
specular reflection geometry. The present invention is not limited
to the arrangement exemplified here in which the information of the
non-specular reflection geometry and specular reflection geometry
are inputted on the same screen. The data input screen illustrated
in FIG. 10 is provided with an input item 30 for the incident light
angle of the non-specular reflection geometry, an input item 31 of
the refection angle of the non-specular reflection geometry, an
input item 32 for the incident light angle of the specular
reflection geometry, and an input item 33 of the refection angle of
the specular reflection geometry. Further, the data input screen
illustrated in FIG. 10 is provided with an OK key 34, a cancel key
35, and a back key 36, which are touch-panel keys. When the cancel
key 35 is pressed, the measurement mode is terminated with the data
input screen inactivated. When the back key 36 is pressed, the
display screen goes back to the data input screen illustrated in
FIG. 9.
[0102] By the input items regarding the non-specular reflection
geometry, the geometry for the fitting process for the internal
reflection light component (Lri) is designated. By the input items
regarding the specular reflection geometry, the geometry for the
fitting process for the surface reflection light component (Lrs) is
designated. The incident light angle and reflection light angle of
the non-specular reflection geometry should be designated
separately. However, the incident light angle and reflection light
angle of the specular reflection geometry are identical, therefore,
a value inputted in one of the input items (e.g., the input item 32
for the incident light angle) is also displayed in the other one of
the input items (e.g., the input item 33 for the reflection light
angle). That is, it is only required to input the value either one
of the input items for the specular reflection geometry.
[0103] After the input of the information regarding the
non-specular reflection geometry and specular reflection geometry,
and the sample on which the toner image is formed is placed on the
gonio data measuring section 104, the OK key 34 is pressed, so that
the processes of S4 to S7 are carried out. Thereby, the lower layer
reflection light component (Lru), internal reflection light
component (Lri), surface reflection light component (Lrs) in each
geometry is calculated out. These values are then stored in the
second memory 152 in association with the geometries.
[0104] The following will describe, in a specific manner, how the
internal reflection light components (Lri) of all geometries are
calculated.
[0105] First, in a display section 122 that displays a data input
screen shown in FIG. 10, the data of an incident light angle and a
light reflection angle of the input non-specular reflection
geometry is supplied to an Lri calculating section 141, and is then
supplied to a gonio data measuring section 104. In the gonio data
measuring section 104, gonio data (Lra) of the geometry thus input
is measured and the data as a result of the measurement is supplied
to the Lri calculating section 141.
[0106] In the Lri calculating section 141, the data of the lower
layer reflection light component (Lru) calculated using the same
geometry is selected and retrieved from the second memory 152, and
the lower layer reflection light component (Lru) is subtracted from
the gonio data (Lra). Furthermore, in this instance, the surface
reflection light component (Lrs) is approximated to 0 and the
remaining reflection light components are used as the internal
reflection light component (Lri).
[0107] The data of the internal reflection light component (Lri)
calculated by the Lri calculating section 141 is supplied to the
Lri fitting process section 142. In the Lri fitting process section
142, the supplied internal reflection light component (Lri) is
subjected to fitting with the Oren-Nayar model. With this, the
internal reflection light component (Lri) of each geometry is
figured out, and the data thus figured out is stored in the second
memory 152.
[0108] The following will specifically describe how the surface
reflection light components (Lrs) of all specular reflection
geometries are calculated.
[0109] First, in the display section 122 that displays a data input
screen shown in FIG. 10, the data of an incident light angle and a
light reflection angle of the input specular reflection geometry is
supplied to the Lrs calculating section 131, and is then supplied
to the gonio data measuring section 104. In the gonio data
measuring section 104, the gonio data (Lrb) of the geometry thus
input is measured, and the data as a result of the measurement is
supplied to the Lrs calculating section 131.
[0110] In the Lrs calculating section 131, the data of the lower
layer reflection light component (Lru) calculated using the same
geometry and the data of the internal reflection light component
(Lri) measured using the same geometry are selected and retrieved
from the second memory 152, and the lower layer reflection light
component (Lru) and the internal reflection light component (Lri)
are subtracted from the gonio data (Lrb).
[0111] The data of the surface reflection light component (Lrs),
which has been calculated as above, is supplied to the Lrs fitting
processing section 132. In the Lrs fitting process section 132, the
surface reflection light component thus supplied is subjected to
fitting with the Torrance-Sparrow model. With this, the surface
reflection light components (Lrs) of all specular reflection
geometries are calculated, and the data obtained by the calculation
is stored in the second memory 152.
[0112] As a result of the processes above, the second memory 152
stores the lower layer reflection light components (Lru), internal
reflection light components (Lri), and surface reflection light
components (Lrs) of all specular reflection geometries. In the
second memory 152, these components are associated with the
corresponding geometries. The specular reflection light component
calculating section 114 adds up the reflection light components
corresponding to the same specular reflection geometry. With this,
the specular reflection light components Lr of all specular
reflection geometries are obtained (S8 in FIG. 8).
[0113] The data as a result of the measurement of the specular
reflection light components Lr is supplied to the operation input
section 102, and displayed on the display section 122. FIG. 11
shows an example of a screen of the display section 122 showing the
measurement result.
[0114] As shown in FIG. 11, after the measurement of the specular
reflection light components Lr, the display section 122 displays: a
graph 40 of the specular reflection light components Lr; an input
item 41 for the specular reflection geometry; a calculation result
42 of the specular reflection light component Lr of the geometry
inputted in the input item 41; an input item 46 for the gloss
threshold; a calculation result 47 of the specular reflection
geometry that indicates the threshold inputted in the input item
46; an OK button 43; a cancel button 44; and a back button 45. The
graph 40 of the specular reflection light components Lr shows the
list of all specular reflection light components Lr, in a case
where the incident light angles are in the range of 10.degree. and
80.degree.. It is therefore possible to see to what extent a sample
specular reflection light component is dependent on the angle. The
results shown in the graph 40 are calculated in the specular
reflection light component calculating section 114 by adding up the
lower layer reflection light components Lru, internal reflection
light components Lri, and surface reflection light components Lrs
of all specular reflection geometries stored in the second memory
152.
[0115] In the specular gloss simulation device 100, an arbitrary
angle is input in the input item 41 of the specular reflection
geometry shown in FIG. 11, and the OK button 43 is pushed. With
this, the value of the specular reflection light component of the
angle thus input is obtained. The calculated value of this case is
equal to a point on the graph 40 of the specular reflection light
components Lr.
[0116] In the meanwhile, a desired specular reflection light
component (corresponding to the luminance, here) is inputted in the
input item 46 for the gloss threshold and the OK button 43 is
pushed. With this, an angle corresponding to the specular
reflection light component thus input is displayed as the
calculation result 47. The calculation result proves that angles
corresponding to the specular reflection light components higher
than the component thus input are higher than the displayed angle.
In other words, the specular gloss simulation device 100 of the
present embodiment makes it possible to calculate the specular
reflection light components of all specular reflection geometries.
Therefore, by varying the specular reflection geometry (incident
and light reflection angles), it is possible to confirm in which
case the specular reflection light component exceeds a
predetermined value. This can be effectively used as a novel
valuation standard for the gloss.
[0117] If the cancel button 44 in the result screen shown in FIG.
11 is pushed, the result screen finishes and the measurement mode
is compulsorily terminated. If the back button 45 is pushed, the
data input screen shown in FIG. 10 is shown again.
[0118] In a case where the specular reflection light component
simulated as above is converted to the gloss in conformity to
Japanese Industrial Standards, the gloss is figured out in such a
manner that a relative value is calculated based on a value in the
case of a standard plate (glass plate with a refractive index of
1.567) specified as a standard sample.
[0119] The specular gloss simulation device 100 may be realized
using a computer system. FIG. 12 shows a computer system 300
capable of executing the functions of the specular gloss simulation
device 100.
[0120] The computer system 300 includes: an image input device 301
such as a flatbed scanner, film scanner, and digital camera; a
computer 302 which performs various processes such as image
processing, by loading a predetermined program (application
software 303); an image display device 304, such as a CRT display
and liquid crystal display, that displays processing results of the
computer 302; and an image output device 305, such as a printer or
the like, which outputs, on a piece of paper or the like, the
processing result of the computer 302. The computer system 300
further includes: a network card or modem as communication means
306 for the connection with a server via a network; a gonio-photo
spectrometer as a gonio data measuring device 307 that measures the
gonio data; a keyboard/mouse 308 by which information input is
performed to cause the computer 302 to conduct a desired process;
an external storage device 309 as external storage means storing
programs and data; or the like.
[0121] To perform the specular gloss simulation of the present
invention by the computer system 300, the computer 302 functions as
the calculating section 101, the gonio data measuring device 307
functions as the gonio data measuring section 104, and the
keyboard/mouse 308 functions as the operation keys 121, and the
image display device 304 functions as the display section 122. The
storage section 103 may be provided in the external storage device
309 or in the computer 302.
[0122] The processing steps performed by the calculating section
101 of the specular gloss simulation device 100 of the present
embodiment and by the sections 11-114 in the calculating section
101 are realized by causing computing means such as a CPU to
execute a program stored in storage means such as ROM (Read Only
Memory) or RAM, so as to control the input means such as a
keyboard, output means such as a display, or a communication means
such as an interface circuit. On this account, the functions and
processes of the specular gloss simulation device 100 can be
realized only by causing the computer having the aforesaid means to
read a storage medium storing the program and execute the program.
If the program is stored in a removable storage medium, the
aforesaid functions and processes can be realized any computer.
[0123] The storage medium may be a program medium such as a memory
(not illustrated) for executing processes on a microcomputer, e.g.
ROM. Alternatively, the storage medium may be a program medium
which is inserted into and read by a program reader provided as the
external storage device 309.
[0124] In any event the stored program is preferably accessed and
executed by a microprocessor. Once read out, the program is
preferably downloaded to a program storage area of the
microcomputer and executed. The program for the download is stored
in the main body device in advance.
[0125] The aforesaid program medium is a storage medium arranged so
that it can be separated from the main body. Examples of such a
program medium include a tape, such as a magnetic tape and a
cassette tape; a magnetic disk, such as a flexible disk and a hard
disk; a disc, such as a CD/MO/MD/DVD; a card, such as an IC card
(inclusive of a memory card); and a semiconductor memory, such as a
mask ROM, an EPROM (erasable programmable read only memory), an
EEPROM (electrically erasable programmable read only memory), or a
flash ROM. All these storage media hold a program in a fixed
manner.
[0126] Alternatively, if a system can be constructed which can
connects to the Internet or other communications network, it is
preferable if the program medium is a storage medium carrying the
program in a flowing manner as in the downloading of a program over
the communications network.
[0127] Further, when the program is downloaded over a
communications network in this manner, it is preferable if the
program for download is stored in a main body device in advance or
installed from another storage medium.
Second Embodiment
[0128] Referring to FIG. 13 through FIG. 19, the following will
describe a Second Embodiment of the present invention. The
foregoing First Embodiment described the specular gloss simulation
method that is applicable regardless of the size of the colorant
material particles of the dye ink, pigment ink, or toner in the
colorant material layer of the sample. However, the present
embodiment describes a specular gloss simulation method and
specular gloss simulation device for more accurately calculating
specular gloss components of the sample when the colorant material
particles contained in the colorant material layer have a
relatively large diameter (i.e., when the colorant material
particles are pigment such as pigment ink or toner). Examples of
such pigment include pigment ink and toner.
[0129] First, the specular gloss simulation device of the present
embodiment is described in regard to the dichromatic reflection
(BRDF) model theory used for the simulation of specular gloss of a
sample. Here, description of the BRDF model will be given through
the case where it is used to calculate reflection light components
of a sample having the bilayer structure of the base material and
the colorant material layer in which toner (pigment) is contained
as colorant material particles.
[0130] FIG. 14 schematizes how the reflection light components of
the bilayer sample are split into individual components. As
illustrated in FIG. 14, a sample 23 includes an upper layer portion
13 constituting a toner image (colorant material layer), and a
lower layer portion 33 constituting a base material such as paper
or a transparent film. According to the dichromatic reflection
(BRDF) model theory, the reflection light components of the light
from a light source 6 include: a surface reflection light component
(Lrss) 27 and an internal reflection light component 35, both from
the upper layer portion 34, and a surface reflection light
component 30 and an internal reflection light component 31, both
from the lower layer portion 33. The composite light of these
components becomes the reflected light from the sample 23. In the
present embodiment, the internal reflection light component 35 from
the upper layer portion 34 can be further divided into a reflection
light component (Lrsp) 28 directly reflected by the colorant
material particles, and a diffuse reflection light component (Lrd)
29 produced by scattering of light between the colorant material
particles. In order to calculate the reflected light components 27
through 31 by the BRDF model, more than one unmeasurable parameter
needs to be estimated.
[0131] However, since the measurement of the internal reflection
light component 31 reflected from the lower layer portion 33 is
difficult, the present invention combines the internal reflection
light component 31 with the surface reflection light component 30
also from the lower layer portion 33, and uses the sum of these
reflection light components as a lower layer reflection light
component (Lru) 32. By calculating the lower layer reflection light
component 32 based on measurement data obtained only from the lower
layer portion 33, a specular reflection light amount can be
accurately calculated for a wide variety of samples images
according to the BRDF model. By thus calculating the lower layer
reflection light component 32 with the surface reflection light
component 27, the reflection light component 28 of the colorant
material particles, and the diffuse reflection light component 29
from the upper layer portion 34, an accurate specular reflection
light amount can be obtained.
[0132] As the BRDF model effective as the mathematical models for
calculating the respective reflection light components, the present
invention can use the (1) Ward Model, (2) Phong Model, (3)
Oren-Nayar Model, and (4) Torrance-Sparrow Model, which are
described in the First Embodiment.
[0133] Of these mathematical models, the Ward model and the Phong
model have been proposed based on isotropic scattering of light,
whereas the Oren-Nayar model and the Torrance-Sparrow model are
based on non-isotropic scattering of light. In the present
embodiment, the Torrance-Sparrow model is adopted as the
mathematical model for calculating the surface reflection light
component 27 and the reflection light component 28 of the colorant
material particles, and the Oren-Nayar model is adopted as the
mathematical model for calculating the diffuse reflection light
component 29 produced by scattering of light between the colorant
material particles. This is because more accurate values can be
obtained when non-isotropic scattering of light is taken into
consideration, though it complicates the equations.
[0134] FIG. 5 represents a geometric arrangement according to the
BRDF model. FIG. 6 represents geometric definitions of object
surfaces according to the BRDF model.
[0135] In calculating the diffuse reflection light component Lrd
using the Oren-Nayar model, mathematical value LrON is calculated
first according to Equation (1) below. LrON = .sigma. .pi. .times.
E0 .times. .times. cos .times. .times. .theta.I [ C1 .function. (
.sigma. ) + cos .function. ( .PHI. .times. .times. r - .PHI.I )
.times. C2 .function. ( .alpha. ; .beta. ; .PHI. .times. .times. r
- .PHI.I ; .sigma. ) .times. tan .times. .times. .beta. ) + ( 1 -
cos .function. ( .PHI. .times. .times. r - .PHI.I ) ) .times. C3
.function. ( .alpha. ; .beta. ; .sigma. ) .times. tan .function. (
.alpha. + .beta. 2 ) + 0.17 .times. .rho. 2 .pi. .times. E0 .times.
.times. cos .times. .times. .theta.I .times. .times. .sigma. 2
.sigma. 2 + 0.13 .function. [ 1 - cos .function. ( .PHI. .times.
.times. r - .PHI.I ) .times. ( 2 .times. .beta. .pi. ) 2 ] .times.
.times. C1 = 1 - 0.5 .times. .times. .sigma. 2 .sigma. 2 + 0.33
.times. .times. C2 = { 0.45 .times. .times. .sigma. 2 .sigma. 2 +
0.09 .times. sin .times. .times. .alpha. ( if .times. .times. cos
.function. ( .PHI. .times. .times. r - .PHI.I ) .gtoreq. 0 ) 0.45
.times. .times. .sigma. 2 .sigma. 2 + 0.09 .times. sin .times.
.times. .alpha. ( sin .times. .times. .alpha. - ( 2 .times. .beta.
.pi. ) 3 ) .times. .times. ( if .times. .times. not ) .times.
.times. C3 = 0.125 .times. ( .sigma. 2 .sigma. 2 + 0.09 ) .times. (
4 .times. .alpha..beta. .pi. 2 ) 2 ( 1 ) ##EQU4##
[0136] In Equation (1), .theta.i is the zenith angle in the light
source direction, oi is the azimuth angle in the light source
direction, .theta.r is the zenith angle in the light reflection
direction, or is the azimuth angle in the light reflection
direction, .sigma. is the roughness variable of the surface
profile, E0 is the radiant luminance incident on the sample, .rho.
is the refractive index of the microscopic surface of the sample
surface, .alpha.=max [.theta.r, .theta.i], and .beta.=min
[.theta.r, .theta.i] (see FIG. 5, FIG. 6). Note that, the
mathematical formula used to calculate LrON in this embodiment is
the same as that used in the First Embodiment.
[0137] In calculating the surface reflection light component Lrss
and the reflection light component Lrsp of the colorant material
particles according to the Torrance-Sparrow model, mathematical
value LrTS (LrTSs and LrTSp) is calculated first according to
Equation (2) below. LrTS = E0 .times. .times. FGAF cos .times.
.times. .theta. .times. .times. r .times. .times. cos .times.
.times. .theta. .times. .times. a .times. c .times. .times. e -
.theta. .times. .times. a 2 2 .times. .sigma. 2 .times. .times. GAF
= max .function. [ 0 , Min .function. [ 1 , 2 < s , n > <
a , n > < s , a > , 2 < v , n > < a , n > <
v , a > ] ] .times. .times. c = .intg. .theta. .times. .times. a
= 0 .pi. 2 .times. .intg. .PHI. .times. .times. a = 0 2 .times.
.pi. .times. e - .theta. .times. .times. a 2 2 .times. .sigma. 2
.times. sin .times. .times. .theta. .times. .times. a .times. d
.PHI. .times. .times. a .times. .times. d .theta. .times. .times. a
( 2 ) ##EQU5##
[0138] In Equation (2), F is the Fresnel reflection index, n is the
normal vector of the sample 3, s is the vector of the light source
direction; v is the vector of the light reflection direction, a is
the bisector vector of s and v, .theta.r is the zenith angle of the
light reflection direction, .theta.a is the zenith angle of vector
a, oa is the azimuth angle of vector a, .sigma. is the roughness
variable of the surface profile, and E0 is the radiant luminance
incident on the sample. Further, in Equation (2), <x, y> (x,
y are arbitrary numbers) is the inner products of the vectors (see
FIG. 5, FIG. 6). The mathematical formula used to calculate LrTS in
this embodiment is the same as that used in the First
Embodiment.
[0139] Subsequently, referring to the flow chart in FIG. 13, a
method will be described by which the amount of specular reflection
light is calculated for each geometry from a measured value of
luminance in a predetermined geometry using the above
technique.
[0140] First, to calculate an lower layer reflection light
component Lru, the transmittance of only the upper layer portion
(toner image) 34 of a sample for which the specular reflection
light component is to be calculated is calculated (step S11). The
measurement geometry here includes a light source, a sample, and a
light receiver positioned along a straight line. In such a
geometry, the light source shines right above the sample. That
light which is received by the light receiver located right under
the sample is measured with a transmission density meter as light
having transmitted the sample. Then, the transmission density Dt
for only the upper layer portion 34 is obtained by calculating a
differential between a sample with a toner image formed thereon (a
sample made up of the upper layer portion 34 and the lower layer
portion 33) and a sample made up of only the lower layer portion
(paper) 33. A transmittance Tt for only the upper layer portion 34
(in other words, the toner image) is given by Tt=10 (-Dt).
[0141] Throughout the following steps, the refractive index
(literature value) of resin which is a main component of toner is
used as the refractive index of the upper layer portion (toner
image) 34.
[0142] Next, a sample with no upper layer portion 34, that is, a
sample with only the lower layer portion 33 (in the present
embodiment, paper or transparent film still carrying no toner image
formed thereon) is prepared. With the light source incidence
direction and the light reflection direction of the sample with
only the lower layer portion 33 being resolved at high resolution,
gonio data is then measured (step S12). Here, CIE 1976 L*a*b* (CIE:
Commission International de l'Eclairage. L* is a lightness, and a*
indicates redness-greenness and b* indicates yellowness-blueness)
color space is used for the measurement. Therefore, the value of L*
is employed as the gonio data.
[0143] The lower layer reflection light component Lru is calculated
from this data (step S13). FIG. 15 is a diagram schematically
illustrating a refraction phenomenon of light and attenuation of an
amount of light, which are taken into consideration when the lower
layer reflection light component Lru is calculated. Light incident
to the sample at an incident light angle .theta.i refracts at the
interface between an air layer 36 and the upper layer portion 34.
This refraction phenomenon obeys Fresnel's theory. The angle
.theta.t after the refraction is given by Fresnel's law
(n1.times.sin .theta.i=n2.times.sin .theta.t, where n1 is the
refractive index of a pre-incidence medium, and n2 the refractive
index of a post-incidence medium). Light is attenuated at the
interface due to the refraction as it passes through the toner
layer. The Fresnel transmittance Tn of that light is given by
equation (3): Tn = [ ( n2 .times. .times. cos .times. .times.
.theta. .times. .times. t n1 .times. .times. cos .times. .times.
.theta.I ) .times. ( 2 .times. n1 .times. .times. cos .times.
.times. .theta.I n2 .times. .times. cos .times. .times. .theta.I +
n1 .times. .times. cos .times. .times. .theta. .times. .times. t )
2 + ( n2 .times. .times. cos .times. .times. .theta. .times.
.times. t n1 .times. .times. cos .times. .times. .theta.I ) .times.
( 2 .times. n1 .times. .times. cos .times. .times. .theta.I n1
.times. .times. cos .times. .times. .theta.I + n2 .times. .times.
cos .times. .times. .theta. .times. .times. t ) 2 ] / 2 ( 3 )
##EQU6##
[0144] As light passes through the upper layer portion 34, the
light is attenuated by the upper layer portion 34 before reaching
the lower layer portion 33. The attenuation obeys the Beer-Lambert
law (-logT=a.times.d, where a is the absorption coefficient of a
colorant material layer, d is the thickness of the colorant
material layer, and T is the transmittance). The length of the
optical path in the upper layer portion 34 traveled by the light
before reaching the lower layer portion 33 changes with the
incident light angle. The apparent transmittance Tt' in accordance
with the changes in the length of the optical path is given by
-logTt'=a.times.(d/cos .theta.i). Light attenuation is evaluated in
terms of the apparent transmittance.
[0145] From the above description, the amount of incident light
reaching the lower layer portion 33 is calculated by evaluating the
attenuation of the amount of light from the apparent transmittance
Tt' in accordance with the Fresnel transmittance Tn and the changes
in the length of the optical path. The calculation also takes into
consideration the changes of the incident light angle of the light
to the lower layer portion 33 caused by the refraction. A similar
optical phenomenon occurs when the reflection from the lower layer
portion 33 travels back to the air layer. Therefore, the lower
layer reflection light component Lru is calculated by calculating
from the gonio data of the sample with only the lower layer portion
(paper) measured in S12 for all incident light angles and light
reflection angles with the two refractions and an attenuation of
light (see FIG. 15) taken into consideration. If the incident light
angle .theta.t after the refraction has decimal places, the angle
is interpolated by proration from the preceding and succeeding
angle values. There are no particular limitations on angle
resolution in the process. Here, the resolution is 1.degree.
because the measuring device has a maximum angle resolution of
1.degree.. To calculate the specular reflection light component
more precisely, the angle resolution is preferably 1.degree. or
less.
[0146] Next, to calculate the diffuse reflection light component
Lrd, the luminance value Lra (L* of CIE 1976 L*a*b*) of the sample
is measured in one certain geometry which contains almost zero
surface reflection light component (step S14). This geometry is
termed the non-specular reflection geometry. Generally, the more
the geometry differs from specular reflection, the smaller the
surface reflection light component. The non-specular reflection
geometry selected here therefore preferably has a large light
source incident light angle and includes a light source incidence
position and a light receiving position in close proximity. For the
present embodiment, an exemplary geometry is selected where the
light source incident light angle .theta.i is 45.degree.
(.phi.i=0.degree.) and the light reflection angle .theta.r is
-60.degree. (.phi.r=0.degree.).
[0147] Next, the density distribution of the toner image sample is
measured, and its roughness variable .sigma.p is calculated from
the measured value (step S15). A specific method for the
calculation of the roughness variable .sigma.p will be detailed
later.
[0148] Subsequently, the lower layer reflection light component Lru
calculated in the same geometry is subtracted from the luminance
value Lra measured in S14. Further, the surface reflection light
component Lrss and the colorant material particle reflection light
component Lrsp are approximated to 0. The remaining reflection
light component is designated the diffuse reflection light
component Lrd. The diffuse reflection light component Lrd thus
obtained is subjected to fitting using an Oren-Nayar model (step
S16). Fitting here means that an unknown parameter is calculated,
and the internal reflection light component is obtained for each
geometry, so that the internal reflection light component
calculated from the luminance value Lra measured in the selected
non-specular reflection geometry can be represented with an
Oren-Nayar model.
[0149] As the roughness variable .sigma. (see FIG. 5) of the
density distribution used in the above process is used a roughness
variable .sigma.p calculated on the basis of the density
distribution of the sample measured in S15. E0 (see FIG. 5) is
irradiance incident to the sample. Here, since the measured value
space is CIE 1976 L*a*b* space, and L* is employed, E0=100.pi..
From these values, the reflectance .rho. of a small plane on the
sample surface is estimated. The reflectance .rho. of the small
plane on the sample surface is never negative in the physical
model; only positive values are employed.
[0150] Inserting these numeric values to equation (1), the
parameters required by the Oren-Nayar model are estimated. Thus, an
Oren-Nayar model calculated value LrON is determined. The magnitude
of the Oren-Nayar model calculated value LrON is also subjected to
fitting by estimating the reflectance parameter .rho. for the small
plane on the sample surface. It is therefore possible to calculate
the diffuse reflection light component Lrd for each geometry
without any particular scaling of the Oren-Nayar model calculated
value LrON. That is, the calculated LrON corresponds to the diffuse
reflection light component Lrd (Lrd=LrON).
[0151] Next, to calculate the surface reflection light component
Lrss and the colorant material particle reflection light component
Lrsp, the luminance value Lrb in one specular reflection geometry
is measured (step S17). The geometry is termed the specular
reflection geometry. The specular reflection geometry selected here
is such that the light source incident light angle is 45.degree.
(.phi.i=0.degree.), and the light reflection angle is 45.degree.
(.phi.r=180.degree.). The present invention is not limited to these
angles.
[0152] Subsequently, the density distribution of the toner image
sample is measured, and its roughness variable .sigma.p is
calculated from the measured value. In addition, the surface shape
of the sample is measured, and its roughness variable .sigma.s is
calculated from the measured value (step S18). The roughness
variable .sigma.p of the density distribution calculated in S15
issued here. A specific method for the calculation of the roughness
variable .sigma.s of the surface shape will be detailed later.
[0153] Next, the lower layer reflection light component Lru
calculated in the same geometry and the diffuse reflection light
component Lrd are subtracted from the luminance value Lrb (L* of
CIE 1976 L*a*b*) measured in S17. The remaining reflection light
component is designated a combined component of the surface
reflection light component Lrss and the colorant material particle
reflection light component Lrsp.
[0154] Then, the model calculated value LrTS is calculated
individually for the surface reflection light component Lrss and
the colorant material particle reflection light component Lrsp
using a Torrance-Sparrow model (step S19).
[0155] The roughness variable .sigma. for the Torrance-Sparrow
model used in the process is a parameter defining the range of the
reflection light component in the physical model. Therefore, for
the surface reflection light component Lrss, the roughness variable
.sigma.s of the surface shape obtained in S18 is employed. For the
colorant material particle reflection light component Lrsp, the
roughness variable .sigma. of the density distribution obtained in
S18 is employed. E0 (see FIG. 5) is 100.pi. similarly to the
Oren-Nayar model. F is set to 1 to obtain surface reflection in the
specular reflection geometry. The Torrance-Sparrow model involves
no estimation parameter. Inputting request parameters determines a
Torrance-Sparrow model calculated value LrTS (that is, the
Torrance-Sparrow model calculated value LrTSs for the surface
reflection light component Lrss and the Torrance-Sparrow model
calculated value LrTSp for the colorant material particle
reflection light component Lrsp).
[0156] Next, fitting is carried out by obtaining respective
allocations from the model calculated values LrTSs and LrTSp so as
to achieve the measured luminance value (step S20). Specifically, a
shape parameter k that satisfies
Lrb=k.times.LrTSs+(1-k).times.LrTSp is calculated, and an
allocation ratio of the surface reflection light component Lrss and
the colorant material particle reflection light component Lrsp is
determined. Thus, the surface, reflection light component Lrss and
the colorant material particle reflection light component Lrsp for
each specular reflection geometry are calculated.
[0157] With these steps, the lower layer reflection light component
Lru, the diffuse reflection light component Lrd, the surface
reflection light component Lrss, and the colorant material particle
reflection light component Lrsp are individually calculated. By
adding these calculate values in the same specular reflection
geometry, the specular reflection light component (amount of
specular reflection light) Lr is obtained (step S21).
[0158] The aforementioned specular gloss simulation method takes
every kind of image (low gloss image, low density image, etc.) into
consideration, and therefore assumes separating a sample on which
measurement is to be made into an upper layer portion and an lower
layer portion. However, special measurement samples (high density,
high gloss samples) may be treated differently. The specular
reflection light component Lr may be calculated using only the
reflection light component from only the upper layer portion (the
surface reflection light component Lrss, the colorant material
particle reflection light component Lrsp, and the diffuse
reflection light component Lrd). This is because in this case, the
lower layer reflection light component Lru is too small to affect
the specular reflection light component Lr.
[0159] In the aforementioned specular gloss simulation method, S1
to S13 are lower layer reflection light component forming steps,
S14 to S16 are internal reflection light component forming steps,
S17 to S19 are surface reflection light component forming steps,
S19 is a shape parameter calculating step, and S20 is a specular
reflection light amount calculating step.
[0160] Next, an arrangement of a specular gloss simulation device
according to the present invention is described below. The specular
gloss simulation device according to the present embodiment
calculates out the specular reflection light component of each
specular reflection geometry by performing the process illustrated
in the flowchart of FIG. 13. From the specular reflection light
components thus obtained, the specular gloss simulation device
simulates the specular gloss. In FIG. 16, an arrangement of a
specular gloss simulation device 200 according to the present
invention is illustrated.
[0161] As illustrated in FIG. 16, the specular gloss simulation
device 200 is provided mainly with a calculating section 201, an
operation input section 202, a storage 203, and a gonio data
measuring section 204.
[0162] The calculating section 201 calculates out a specular
reflection light component from (a) data of refractive index and
transmittance, the variable of the density distribution on the
sample, the variable of the surface coarseness of the sample (which
has been inputted via the operation input section 202) of the upper
portion (toner image) 34, (b) non-specular reflection
geometry/specular reflection geometry being designated via the
operation input section 202, and (c) gonio data being measured by
the gonio data measuring section 204.
[0163] The calculating section 201 is provided with a lower layer
reflection light component calculating section (lower layer
reflection light component creating section) 211, a diffuse
reflection light component creating section (internal reflection
light component creating section) 262, a surface reflection light
component creating section 213, and a specular reflection light
component calculating section (specular reflection light amount
calculating section) 214. The lower layer reflection light
component calculating section 211 is used for calculating a lower
layer reflection light components (Lru) in each geometry. The
diffuse reflection light component creating section 262 is used for
calculating an internal reflection light component (Lri) from a
measured gonio data in one non-specular reflection geometry, and
performing fitting process to fit the thus calculated internal
reflection light component (Lri) to the Oren-Nayar model thereby to
obtain the diffuse reflection light component (Lrd) which is an
internal reflection light component in each geometry. The surface
reflection light component creating section 213 is used for
calculating a surface reflection light component (Lrss) from a
measured gonio data in one specular reflection geometry, and
performing fitting process to fit the thus calculated surface
reflection light component (Lrs) to the Torrance-Sparrow model
thereby to obtain a surface reflection light component (Lrss) in
each specular reflection geometry. The specular reflection light
component calculating section (specular reflection light amount
calculating section) 214 is used for calculating a specular
reflection light component (specular reflection light amount) (Lr)
by adding up the reflection light components thus obtained via the
respective sections. The specular reflection light component
calculating section 214 adds up the reflection light components of
the same specular reflection geometry thereby to calculate out the
specular reflection light component in each specular reflection
geometry.
[0164] In the present embodiment, the internal reflection light
component 35 is considered such that it is made up with the
colorant material particle reflection light component (Lrsp) 28 and
the diffuse reflection light component (Lrd) 29. The colorant
material particle reflection light component (Lrsp) 28 is
calculated from the colorant material particle reflection light
component (Lrsp) 28 based on the gonio data measured in one
specular reflection geometry. Therefore, the calculating section
201 is further provided with a colorant material particle
reflection light component creating section 261 for calculating the
colorant material particle reflection light component (Lrsp) 28
from gonio data measured in one specular reflection geometry, and
performing fitting process to fit the thus calculated colorant
material particle reflection light component (Lrsp) 28 to the
Torrance-Sparrow model thereby to create the colorant material
particle reflection light component (Lrsp) 28 in each specular
reflection geometry.
[0165] Moreover, the colorant material particle reflection light
component creating section 261 is provided with an Lrsp calculating
section (not shown) for calculating the colorant material particle
reflection light component from the measured gonio data in one
specular reflection geometry, and an Lrsp fitting process section
(not shown) for performing fitting process to fit the thus
calculated colorant material particle reflection light component
(Lrsp) to the Torrance-Sparrow mode thereby to obtain the colorant
material particle reflection light component (Lrsp) in each
specular reflection geometry. Moreover, the diffuse reflection
light component creating section 262 is provided with an Lrd
calculating section (not shown) for calculating the diffuse
reflection light component from the gonio data measured in one
non-specular reflection geometry, and an Lrd fitting process
section (not shown) for performing fitting process to fit the thus
calculated diffuse reflection light component to the Oren-Nayar
model thereby to obtain the diffuse reflection light component in
each geometry.
[0166] Moreover, the surface reflection light component creating
section 213 is provided with an Lrss calculating section (not
shown) for calculating the surface reflection light component
(Lrss) from the measured gonio data in one specular reflection
geometry, and an Lrss fitting process section (not shown) for
performing fitting process to apply the thus calculated surface
reflection light component (Lrss) in the Torrance-Sparrow mode
thereby to obtain the surface reflection light component (Lrss) in
each specular reflection geometry.
[0167] In the present embodiment, the measured gonio data in one
specular reflection geometry is allocated to the surface reflection
light component (Lrss) and the colorant material particle
reflection light component (Lrsp). Therefore, the calculating
section 201 is provided with a shape-parameter calculating section
215 for determining how the measured gonio data is allocated to the
surface reflection light component (Lrss) and the colorant material
particle reflection light component (Lrsp).
[0168] The operation input section 202 is used for inputting
various numerical values necessary for the calculation of the
specular reflection light component, and for displaying a result of
calculation performed by the calculating section 201. The operation
input section 202 includes operation keys 221 for inputting
numerical values and/or the like, and a display section 222 for
displaying items such as information inputted via the operation
keys 221, the result of calculation, and/or the like.
[0169] The storage section 203 is used for storing therein a result
of the measurement performed by the gonio data measuring section
204, and the result of the calculation performed by the calculating
section 201. The storage section 203 is provided with a first
memory 251 (LUT 1) and a second memory 252 (LUT 2). The first
memory 251 is for storing therein gonio data of a sample measured
by the gonio data measuring section 204, the sample having a lower
layer portion (paper) 33 only. The second memory 252 is for storing
therein each reflection light component calculated out by the
calculating section 201.
[0170] The gonio data measuring section 204 measures the gonio data
of the sample having the lower layer portion (paper) 33 only, and
the gonio data of the sample having the two-layered structure, that
is, having the lower layer portion 33 and the upper layer portion
(toner image) 34. The gonio data measuring section 204 has an
angular resolution of 1.degree., by which the gonio data measuring
section 204 is able to measure the gonio data per degree. For
simulating the specular glossiness by using the specular gloss
simulation device 200, the gonio data of the sample having the
lower layer portion (paper) 33 only is measured per degree,
meanwhile for the sample having the lower layer portion 33 and the
upper layer portion 34, it is only required to measure the gonio
data of one specular reflection geometry and one non-specular
reflection geometry.
[0171] Next, how to simulate the specular gloss in each specular
reflection geometry of a sample by using the specular gloss
simulation device 200 is described below, referring to FIGS. 13 and
16.
[0172] Firstly, transmittance and refractive index of an upper
layer portion of a sample (toner image) are measured (at S1 in FIG.
11). The transmittance and refractive index are to be inputted into
the specular gloss simulation device 200 in order to measure the
specular gloss component. Transmittance Tt is calculated out from
Equation Tt=10 (-Dt), where Dt is a transmission density of only
the upper layer portion. The transmission density is worked out by
obtaining a difference between transmission density of the sample
on which the toner image is formed (i.e., the sample having the
lower layer portion 33 and the upper layer portion 34) and that of
the sample having the lower layer portion (paper) 33 only. A
transmission density meter is used to measure the transmission
density of the sample on which the toner image is formed (i.e., the
sample having the lower layer portion 33 and the upper layer
portion 34) and that of the sample having the lower layer portion
(paper) 33 only. The measurement of the transmission density may be
carried out with a X-rite model 820 transmission densitometer made
by X-rite Inc.
[0173] In the following process a refractive index (literature
value) of a resin which is a main component of the toner is used as
the refractive index of the upper layer portion (toner image)
34.
[0174] Next, a shape of the toner layer surface is measured, by
using a shape-measuring microscope VK-9500 (manufactured by KEYENCE
corp.) and a variable of a toner layer surface coarseness is
calculated based on height information (data regarding Z-axis
direction, where a plane of the sample is an X,Y plane) obtained
from the measurement. Slope of a microscopic surface of the toner
layer surface is calculated based on the height information of an
adjacent picture element. Then, after the slope of the microscopic
surface is plotted in a histogram, a standard deviation of the
slope of the microscopic surface is calculated within a range of
2.sigma. (95.5% of the data) thereby to obtain the variable
.sigma.s of roughness of colorant material layer.
[0175] Meanwhile, a transmission image (i.e. an image obtained from
transmissive light) for the sample is obtained by using a CCD
camera CS-3910 (manufactured by Tokyo Electronic Industry) and a
transmission-use light source whose amount of light output is 200
W, and the variable of evenness in density is calculated from the
obtained transmission image data. The sample is placed between the
CCD camera and the transmission-use light source. In other words,
where the sample is X, Y plane, the CCD camera and the
transmission-use light source are placed in the Z-direction. Then,
the transmission image is obtained. Density of the picture elements
of thus obtained transmission image is plotted in a histogram.
Then, a standard deviation of transmission density is calculated
within a range of 2.sigma. (95.5% of the data) thereby to obtain
the variable .sigma.p of density distribution.
[0176] Here, the variable .sigma.p of the density distribution and
the variable .sigma.s of roughness of surface shape of the sample
are respectively measured in S15 and S17 of the flowchart of FIG.
13. When using the specular gloss simulation device 200 of the
present invention for evaluating the specular gloss, the variables
are measured in advance by using a separate device, and these
variables are inputted at the same time the transmittance and the
refractive index are inputted.
[0177] Next, the transmittance, the variables .sigma.p and .sigma.s
and the refractive index of the upper portion 34 of the sample thus
measured by the above methods are inputted via the operation keys
221 of the operation input section 202. FIG. 17 illustrates an
example of a data input screen displayed on the display section 222
of the specular gloss simulation device 200. On the data input
screen illustrated in FIG. 17, an input item 50 for the refractive
index of the upper portion of the sample to be measured and an
input item 51 for transmittance of the sample to be measured, an
input item 52 for the variable of the roughness of the surface
shape of the sample to be measured, and an input item 53 for the
variable of density distribution of the sample to be measured are
displayed. Further, an OK key 54, and a cancel key 55 are displayed
on the data input screen illustrated in FIG. 17, which are
touch-panel keys. Via the operation keys 221, the transmittance,
the refractive index, and the variables .sigma.p and .sigma.s thus
obtained by the above methods are inputted respectively into the
input items 50 to 53 on the display section 222. If the cancel key
55 is pressed on this data input screen, a measurement mode is
terminated with the data input screen inactivated.
[0178] Then, a base material made of the same material as that of
the base material of the sample to be measured (i.e., the sample
having the lower layer portion) is put in the gonio data measuring
section 204 of the specular gloss simulation device 200, then the
OK key 54 is pressed. In this way, the gonio data measuring section
204 measures the gonio data (CIE 1976*a*b*L*) of the sample having
only the lower portion (at S12 in FIG. 13). The gonio data thus
measured is stored in the first memory 251 of the storage section
203.
[0179] As the gonio data measuring section 204, gonio-photo
spectrometer GSP-2S (made by Murakami Shikisai) may be used, for
example. Moreover, the gonio data measurement of the sample having
only the lower portion has the angular resolution of 1.degree. with
respect to the light source incident light angle and reflection
light angle. Therefore, the first memory 251 stores the gonio data
in association with the incident light angle and the reflection
light angle, the gonio data being measured at the incident light
angle and the reflection light angle per degree.
[0180] Next, based on the refractive index theory and attenuation
theory, the lower layer reflection light component calculating
section 211 calculates the lower layer reflection light component
(Lru) in each geometry from the refractive index and transmittance
of the upper layer portion which are inputted via the operation
input section 202, and the gonio data stored in the first memory
251 (at S13 in FIG. 13). The lower layer reflection light component
(Lru) thus calculated is then stored in the second memory 252 in
the storage section 203.
[0181] After that, a similar process is carried out for a given
non-specular reflection geometry selected. Information on the
non-specular reflection geometry is inputted via the operation
input section 202, and then the gonio data in the non-specular
reflection geometry is measured (at S14 in FIG. 13). From the gonio
data thus measured, the diffuse reflection light component (Lrd) of
the non-specular reflection geometry is calculated out. Then,
fitting process carried out in which the internal reflection light
component (Lri) of the non-specular reflection geometry is applied
in the Oren-Nayar model, thereby to obtain the diffuse reflection
light component (Lrd) in each geometry (at S16 in FIG. 13). The
variable .sigma. of evenness in density for use in calculating the
diffuse reflection light component (Lrd) is that variable .sigma.p
of evenness in density of the sample which is inputted, in advance,
via the operation input section 202.
[0182] Further, a similar process is carried out for a given
specular reflection geometry selected. Information on the specular
reflection geometry is inputted via the operation input section
102, and then the gonio data in the specular reflection geometry
(at S17 in FIG. 13). From the gonio data thus measured, the surface
reflection light component (Lrs) and the colorant material particle
reflection light component (Lrsp) 28 of the specular reflection
geometry are calculated out (at S19 in FIG. 13). In other words, a
Torrance-Sparrow model calculation value LrTSs of the surface
reflection light component Lrss and a Torrance-Sparrow model
calculation value LrTSp of colorant material particle reflection
light component Lrsp are calculated. The variable .sigma. of the
density distribution for use in calculating the colorant material
particle reflection light component (Lrsp) is the variable .sigma.p
of evenness in density of the sample. This variable is inputted, in
advance, via the operation input section 202. The variable .sigma.
of the surface coarseness for use in calculating the surface
reflection light component (Lrss) is the variable .sigma.s of the
surface coarseness of the sample. This variable is also inputted,
in advance, via the operation input section 202.
[0183] Then, fitting process is carried out in which the surface
reflection light component (Lrs) and the colorant material particle
reflection light component (Lrsp) of one specular reflection
geometry are fitted to the Torrance-Sparrow model, thereby to
obtain the surface reflection light component (Lrs) and the
colorant material particle reflection light component (Lrsp) in
each specular reflection geometry (at S20 in FIG. 13). In other
words, the shape-parameter calculating section 215 finds allocation
from the foregoing model calculation values LrTSs and LrTSp thereby
to obtain, based on the allocation, the surface reflection light
component Lrss and the colorant material particle reflection light
component Lrsp in each specular reflection geometry.
[0184] FIG. 18 gives an example of the data input screen displayed
on the display section 222, for the input of the information
regarding the selected non-specular reflection geometry and
specular reflection geometry. The present invention is not limited
to the arrangement exemplified here in which the information of the
non-specular reflection geometry and specular reflection geometry
are inputted on the same screen. The data input screen illustrated
in FIG. 18 is provided with an input item 60 for the incident light
angle of the non-specular reflection geometry and an input item 61
of the refection angle of the non-specular reflection geometry, an
input item 62 for the incident light angle of the specular
reflection geometry and an input item 63 of the refection angle of
the specular reflection geometry. Further, the data input screen
illustrated in FIG. 18 is provided with an OK key 64, a cancel key
65, and a back key 66, which are touch-panel keys. When the cancel
key 65 is pressed, the measurement mode is terminated with the data
input screen inactivated. When the back key 66 is pressed, the
display screen goes back to the data input screen illustrated in
FIG. 17.
[0185] By the input items regarding the non-specular reflection
geometry, the geometry for the fitting process for the diffuse
reflection light component (Lrd) is designated. By the input items
regarding the specular reflection geometry, the geometry for the
fitting process for the surface reflection light component (Lrss)
is designated. The incident light angle and reflection light angle
of the non-specular reflection geometry should be designated
separately. However, the incident light angle and reflection light
angle of the specular reflection geometry are identical, therefore,
a value inputted in one of the input items (e.g., the input item 62
for the incident light angle) is also displayed in the other one of
the input items (e.g., the input item 63 for the reflection light
angle). That is, it is only required to input the value either one
of the input items for the specular reflection geometry.
[0186] After the input of the information regarding the
non-specular reflection geometry and specular reflection geometry,
and the sample on which the toner image is formed is placed on the
gonio data measuring section 204, the OK key 64 is pressed, so that
the processes of S14 to S20 are carried out (S15 and S17 are
omitted since these steps are carried out in advance by using a
separate device). Thereby, the lower layer reflection light
component (Lru), diffuse reflection light component (Lrd), the
surface reflection light component (Lrss), and the colorant
material particle reflection light component (Lrsp) 28 in each
geometry is calculated out. These values are then stored in the
second memory 252 in association with the geometries.
[0187] The following will describe, in a specific manner, how the
internal reflection light components (Lrd) of all geometries are
calculated.
[0188] First, in the display section 222 that displays a data input
screen shown in FIG. 18, the data of an incident light angle and a
light reflection angle of the input non-specular reflection
geometry is supplied to a Lrd calculating section (not
illustrated), and is then supplied to the gonio data measuring
section 204. In the gonio data measuring section 204, the gonio
data (Lra) of the geometry thus input is measured, and the data as
a result of the measurement is supplied to the Lrd calculating
section.
[0189] In the Lrd calculating section, the data of the lower layer
reflection light component (Lru) calculated using the same geometry
is selected and retrieved from the second memory 252, and this
lower layer reflection light component (Lru) is subtracted from the
gonio data (Lra). Further, in this instance, the diffuse reflection
light component (Lrd) is approximated to 0 and the remaining
reflection light components are regarded as the internal reflection
light component (Lrd).
[0190] The data of the diffuse reflection light component (Lrd)
calculated by the Lrd calculating section is supplied to the Lrd
fitting process section (not illustrated). In the Lrd fitting
process section, the surface reflection light component thus
supplied is subjected to fitting with the Oren-Nayar model. With
this, the internal reflection light components (Lrs) of all
geometries are calculated, and this data is stored in the second
memory s52.
[0191] The following will specifically describe how the reflection
light components (Lrsp) of colorant material particles and the
surface reflection light components (Lrss), of all specular
reflection geometries, are calculated.
[0192] First, in the display section 222 that displays a data input
screen shown in FIG. 18, the data of an incident light angle and a
light reflection angle of the input specular reflection geometry is
supplied to an Lrss calculating section and a Lrsp calculating
section (both not illustrated), and the data is then supplied to
the gonio data measuring section 204. In the gonio data measuring
section 204, the gonio data (Lrb) of the geometry thus input is
measured and the data as a result of the measurement is supplied to
the Lrss calculating section and the Lrsp calculating section.
[0193] In the Lrss calculating section, the data of the lower layer
reflection light component (Lru) calculated using the same geometry
and the data of the diffuse reflection light component (Lrd)
calculated using the same geometry are selected and retrieved from
the second memory 252. The lower layer reflection light component
(Lru) and the diffuse reflection light component (Lrd) are
subtracted from the gonio data (Lrb), and a model calculation value
(LrTSs) is calculated using the Torrance-Sparrow model.
[0194] In the Lrsp calculating section, the data of the lower layer
reflection light component (Lru) calculated using the same geometry
and the data of the diffuse reflection light component (Lrd)
calculated by the same geometry are selected and retrieved from the
second memory 252. The lower layer reflection light component (Lru)
and the diffuse reflection light component (Lrd) are subtracted
from the gonio data (Lrb), and a model calculation value (LrTSp) is
calculated using the Torrance-Sparrow model.
[0195] In the configuration parameter calculating section 215, a
configuration parameter k that satisfies
Lrb=k.times.LrTSs+(1-k).times.LrTSp is calculated in reference to
the model calculation values (LrTSs) and (LrTSp) thus calculated
and the gonio data (Lrb), and a distribution ratio between the
surface reflection light component (Lrss) and the reflection light
component Lrsp of the colorant material particles is determined.
With this, the surface reflection light component (Lrss) and the
reflection light component (Lrsp) of the colorant material
particles, of one specular reflection geometry, are determined.
[0196] The data of the surface reflection light component (Lrss)
and the data of the reflection light component (Lrsp) of colorant
material particles, which have been calculated as above, are sent
to a Lrss fitting process section (not illustrated) and a Lrsp
fitting process section (not illustrated), respectively. In the
Lrss fitting process section and the Lrsp fitting process section,
the surface reflection light component (Lrss) and reflection light
component (Lrsp) thus supplied are subjected to the fitting with
the Torrance-Sparrow model. With this, the surface reflection light
components (Lrss) and the reflection light components (Lrsp) for
all of the specular reflection geometry are calculated, and the
data as a result of the calculation is stored in the second memory
252.
[0197] As a result of the processes above, the second memory 252
stores the lower layer reflection light components (Lru), the
diffuse reflection light components (Lrd), and the reflection light
components (Lrsp) of the colorant material particle, which are of
all of the geometries. These components in the second memory 252
are associated with the corresponding specular reflection
geometries. The specular reflection light component calculating
section 214 adds up the reflection light components of the same
specular reflection geometry. With this, the specular reflection
light components Lr of all specular reflection geometries are
obtained (S21 in FIG. 13).
[0198] The data of the measurement result of the specular
reflection light components Lr obtained above is sent to the
operation input section 202, and displayed on the display section
222. FIG. 19 shows an example of the measurement result displayed
on the display section 222.
[0199] As shown in FIG. 19, after the measurement of the specular
reflection light components Lr, the display section 222 displays: a
graph 70 of the specular reflection light components Lr; an input
item 71 for the specular reflection geometry; a calculation result
72 of the specular reflection light component Lr of the geometry
inputted in the input item 71; an input item 73 for the gloss
threshold; a calculation result 74 of the specular reflection
geometry that indicates the threshold inputted in the input item
73; an OK button 75; a cancel button 76; and a back button 77. The
graph 70 of the specular reflection light components Lr shows the
list of all specular reflection light components Lr, in a case
where the incident light angles are in the range of 10.degree. and
80.degree.. It is therefore possible to see to what extent a sample
specular reflection light component is dependent on the angle. The
results shown in the graph 70 are calculated in the specular
reflection light component calculating section 214 by adding up the
lower layer reflection light components Lru, diffuse reflection
light components Lrd, surface reflection light components Lrss, and
reflection light components Lrsp of the colorant material particle,
of all specular reflection geometries stored in the second memory
252.
[0200] In the specular gloss simulation device 200, an arbitrary
angle is input in the input item 71 of the specular reflection
geometry shown in FIG. 19, and the OK button 75 is pushed. With
this, the value of the specular reflection light component of the
angle thus input is, obtained. The calculated value of this case is
equal to a point on the graph 70 of the specular reflection light
components Lr.
[0201] In the meanwhile, a desired specular reflection light
component (corresponding to the luminance, here) is inputted in the
input item 73 for the gloss threshold and the OK button 75 is
pushed. With this, an angle corresponding to the specular
reflection light component thus input is displayed as the
calculation result 74. The calculation result proves that angles
corresponding to the specular reflection light components higher
than the component thus inputted are greater than the displayed
angle. In other words, the specular gloss simulation device 200 of
the present embodiment makes it possible to calculate the specular
reflection light components of all specular reflection geometries.
Therefore, by varying the specular reflection geometry (incident
and light reflection angles), it is possible to confirm in which
case the specular reflection light component exceeds a
predetermined value. This can be effectively used as a novel
valuation standard for the gloss.
[0202] If the cancel button 76 in the result screen shown in FIG.
19 is pushed, the result screen finishes and the measurement mode
is compulsorily terminated. If the back button 77 is pushed, the
data input screen shown in FIG. 18 is shown again.
[0203] In a case where the specular reflection light component
simulated as above is converted to the gloss in conformity to
Japanese Industrial Standards, the gloss is figured out in such a
manner that a relative value is calculated based on a value in the
case of a standard plate (glass plate with a refractive index of
1.567) specified as a standard sample.
[0204] The specular gloss simulation device 200 may be realized
using a computer system. The computer system may be similar to the
computer system 300 (see FIG. 12) of Embodiment 1.
[0205] As in the case of Embodiment 1, the processing steps
performed by the calculating section 201 of the specular gloss
simulation device 200 of the present embodiment and the processing
steps performed by the sections 21-215 in the calculating section
201 are realized by causing computing means such as a CPU to
execute a program stored in storage means such as ROM (Read Only
Memory) and RAM, so as to control the input means such as a
keyboard, output means such as a display, or a communication means
such as an interface circuit. On this account, the functions and
processes of the specular gloss simulation device 200 can be
realized only by causing the computer having the aforesaid means to
read a storage medium storing the program and execute the program.
If the program is stored in a removable storage medium, the
aforesaid functions and processes can be realized on any
computer.
Third Embodiment
[0206] Referring to FIG. 24 through FIG. 28, the following will
describe a Third Embodiment of the present invention. The foregoing
First Embodiment described the specular gloss simulation method
that is applicable regardless of the size of the colorant material
particles in the dye ink, pigment ink, or toner used for the
colorant material layer of the sample. However, as in the Second
Embodiment, the present embodiment describes a specular gloss
simulation method and specular gloss simulation device for more
accurately calculating specular gloss components of the sample when
the colorant material particles contained in the colorant material
layer have a relatively large diameter (i.e., when the colorant
material particles are pigments such as pigment ink or toner).
Examples of such pigments include pigment ink and toner. Note that,
the present embodiment differs from the foregoing First and Second
Embodiments in that one of the specular reflection geometries and
two of the non-specular reflection geometries are selected as the
given geometry, and gonio data of these geometries are
measured.
[0207] First, the specular gloss simulation device of the present
embodiment is described in regard to the dichromatic reflection
(BRDF) model theory used for the simulation of specular gloss of a
sample. Here, description of the BRDF model will be given through
the case where it is used to calculate reflection light components
of a sample having the bilayer structure of the base material and
the colorant material layer in which toner (pigment) is contained
as colorant material particles.
[0208] FIG. 14 schematizes how the reflection light components of
the bilayer sample are split into individual components. As
illustrated in FIG. 14, a sample 23 includes an upper layer portion
13 constituting a toner image (colorant material layer), and a
lower layer portion 33 constituting a base material such as paper
or a transparent film. According to the dichromatic reflection
(BRDF) model theory, the reflection light components of the light
from a light source 6 include: a surface reflection light component
(Lrss) 27 and an internal reflection light component 35, both from
the upper layer portion 34, and a surface reflection light
component 30 and an internal reflection light component 31, both
from the lower layer portion 33. The composite light of these
components becomes the reflected light from the sample 23. In the
present embodiment, the internal reflection light component 35 from
the upper layer portion 34 can be further divided into a reflection
light component (Lrsp) 28 directly reflected by the colorant
material particles, and a diffuse reflection light component (Lrd)
29 produced by scattering of light between the colorant material
particles. In order to calculate the reflected light components 27
through 31 by the BRDF model, more than one unmeasurable parameter
needs to be estimated.
[0209] However, since the measurement of the internal reflection
light component 31 reflected from the lower layer portion 33 is
difficult, the present invention combines the internal reflection
light component 31 with the surface reflection light component 30
also from the lower layer portion 33, and uses the sum of these
reflection light components as a lower layer reflection light
component (Lru) 32. By calculating the lower layer reflection light
component 32 based on measurement data obtained only from the lower
layer portion 33, a specular reflection light amount can be
accurately calculated for a wide variety of samples images
according to the BRDF model. By thus calculating the lower layer
reflection light component 32 with the surface reflection light
component 27, the reflection light component 28 of the colorant
material particles, and the diffuse reflection light component 29
from the upper layer portion 34, an accurate specular reflection
light amount can be obtained.
[0210] As the BRDF model effective as the mathematical models for
calculating the respective reflection light components, the present
invention can use the (1) Ward Model, (2) Phong Model, (3)
Oren-Nayar Model, and (4) Torrance-Sparrow Model, which are
described above in the First Embodiment.
[0211] Of these mathematical models, the Ward model and the Phong
model have been proposed based on isotropic scattering of light,
whereas the Oren-Nayar model and the Torrance-Sparrow model are
based on non-isotropic scattering of light. In the present
embodiment, the Torrance-Sparrow model is adopted as the
mathematical model for calculating the surface reflection light
component 27 and the reflection light component 28 of the colorant
material particles, and the Oren-Nayar model is adopted as the
mathematical model for calculating the diffuse reflection light
component 29 produced by scattering of light between the colorant
material particles. This is because more accurate values can be
obtained when non-isotropic scattering of light is taken into
consideration, though it complicates the equations.
[0212] FIG. 5 represents a geometric arrangement according to the
BRDF model. FIG. 6 represents geometric definitions of object
surfaces according to the BRDF model.
[0213] In calculating the diffuse reflection light component Lrd
using the Oren-Nayar model, mathematical value LrON is calculated
first according to Equation (1) below. LrON = .sigma. .pi. .times.
E0 .times. .times. cos .times. .times. .theta.I [ C1 .function. (
.sigma. ) + cos .function. ( .PHI. .times. .times. r - .PHI.I )
.times. C2 .function. ( .alpha. ; .beta. ; .PHI. .times. .times. r
- .PHI.I ; .sigma. ) .times. tan .times. .times. .beta. ) + ( 1 -
cos .function. ( .PHI. .times. .times. r - .PHI.I ) ) .times. C3
.function. ( .alpha. ; .beta. ; .sigma. ) .times. tan .function. (
.alpha. + .beta. 2 ) + 0.17 .times. .rho. 2 .pi. .times. E0 .times.
.times. cos .times. .times. .theta.I .times. .times. .sigma. 2
.sigma. 2 + 0.13 .function. [ 1 - cos .function. ( .PHI. .times.
.times. r - .PHI.I ) .times. ( 2 .times. .beta. .pi. ) 2 ] .times.
.times. C1 = 1 - 0.5 .times. .times. .sigma. 2 .sigma. 2 + 0.33
.times. .times. C2 = { 0.45 .times. .times. .sigma. 2 .sigma. 2 +
0.09 .times. sin .times. .times. .alpha. ( if .times. .times. cos
.function. ( .PHI. .times. .times. r - .PHI.I ) .gtoreq. 0 ) 0.45
.times. .times. .sigma. 2 .sigma. 2 + 0.09 .times. sin .times.
.times. .alpha. ( sin .times. .times. .alpha. - ( 2 .times. .beta.
.pi. ) 3 ) .times. .times. ( if .times. .times. not ) .times.
.times. C3 = 0.125 .times. ( .sigma. 2 .sigma. 2 + 0.09 ) .times. (
4 .times. .alpha..beta. .pi. 2 ) 2 ( 1 ) ##EQU7##
[0214] In Equation (1), .theta.i is the zenith angle in the light
source direction, oi is the azimuth angle in the light source
direction, .theta.r is the zenith angle in the light reflection
direction, or is the azimuth angle in the light reflection
direction, .sigma. is the roughness variable of the surface
profile, E0 is the radiant luminance incident on the sample, .rho.
is the refractive index of the microscopic surface of the sample
surface, .alpha.=max [.theta.r, .theta.i], and .beta.=min
[.theta.r, .theta.i] (see FIG. 5, FIG. 6). Note that, the
mathematical formula used to calculate LrON in this embodiment is
the same as those used in the First and Second Embodiments.
[0215] In calculating the surface reflection light component Lrss
and the reflection light component Lrsp of the colorant material
particles according to the Torrance-Sparrow model, mathematical
value LrTS (LrTSs and LrTSp) is calculated first according to
Equation (2) below. LrTS = E0 .times. .times. FGAF cos .times.
.times. .theta. .times. .times. r .times. .times. cos .times.
.times. .theta. .times. .times. a .times. c .times. .times. e -
.theta. .times. .times. a 2 2 .times. .sigma. 2 .times. .times. GAF
= max .function. [ 0 , Min .function. [ 1 , 2 < s , n > <
a , n > < s , a > , 2 < v , n > < a , n > <
v , a > ] ] .times. .times. c = .intg. .theta. .times. .times. a
= 0 .pi. 2 .times. .intg. .PHI. .times. .times. a = 0 2 .times.
.pi. .times. e - .theta. .times. .times. a 2 2 .times. .sigma. 2
.times. sin .times. .times. .theta. .times. .times. a .times. d
.PHI. .times. .times. a .times. .times. d .theta. .times. .times. a
( 2 ) ##EQU8##
[0216] In Equation (2), F is the Fresnel reflection index, n is the
normal vector of the sample 3, s is the vector of the light source
direction, v is the vector of the light reflection direction, a is
the bisector vector of s and v, .theta.r is the zenith angle of the
light reflection direction, .theta.a is the zenith angle of vector
a, oa is the azimuth angle of vector a, .sigma. is the roughness
variable of the surface profile, and E0 is the radiant luminance
incident on the sample. Further, in Equation (2), <x, y> (x,
y are arbitrary numbers) is the inner products of the vectors (see
FIG. 5, FIG. 6). Note that, the mathematical formula used to
calculate LrTS in this embodiment is the same as those used in the
First and Second Embodiments.
[0217] Subsequently, referring to the flow chart in FIG. 24, a
method will be described by which the amount of specular reflection
light is calculated for each geometry from a measured value of
luminance in a predetermined geometry using the above
technique.
[0218] First, to calculate the lower layer reflection light
component Lru, the transmittance of only the upper layer portion
(toner image) 34 of a sample for which the specular reflection
light component is to be calculated is calculated (step S21). The
measurement geometry here includes a light source, a sample, and a
light receiver positioned along a straight line. In such a
geometry, the light source shines right above the sample. That
light which is received by the light receiver located right under
the sample is measured with a transmission density meter as light
having transmitted the sample. Here, the transmission density Dt
for only the upper layer portion 34 is obtained by making
measurements on a sample with a toner image formed thereon (a
sample made up of the upper layer portion 34 and the lower layer
portion 33) and a sample made of only the lower layer portion
(paper) 33 with a transmission density meter and calculating a
differential between the former and the latter. A transmittance Tt
for only the upper layer portion 34 (in other words, the toner
image) is given by Tt=10 (-Dt).
[0219] Throughout the following steps, the refractive index
(literature value) of resin which is a main component of toner is
used as the refractive index of the upper layer portion (toner
image) 34.
[0220] Next, a sample with no upper layer portion 34, that is, a
sample with only the lower layer portion 33 (in the present
embodiment, paper or transparent film still carrying no toner image
formed thereon) is prepared. With the light source incidence
direction and the light reflection direction of the sample with
only the lower layer portion 33 being resolved at high resolution,
gonio data is then measured (step S22). Here, CIE 1976 L*a*b* (CIE:
Commission International de l'Eclairage. L* is a lightness, and a*
indicates redness-greenness and b* indicates yellowness-blueness)
color space is used for the measurement. Therefore, the value of L*
is employed as the gonio data. There are no particular limitations
on angle resolution in the process. In the present embodiment, the
resolution is 1.degree. because typical measuring devices have a
maximum angle resolution of 1.degree.. In other words, in the
present embodiment, the gonio data is measured for all geometries
in which the angles shown in FIG. 5 are shifted by 1.degree.. To
calculate the specular reflection light component more precisely,
the angle resolution is preferably 1.degree. or less.
[0221] The lower layer reflection light component Lru is calculated
for each geometry from this data (step S23). FIG. 15 is a diagram
schematically illustrating a refraction phenomenon of light and
attenuation of an amount of light, which are taken into
consideration when the lower layer reflection light component Lru
is calculated. Light incident to the sample at an incident light
angle .theta.i refracts at the interface between the air layer 36
and the upper layer portion 34. This refraction phenomenon obeys
Fresnel's theory. The angle .theta.t after the refraction is given
by Fresnel's law (n1.times.sin .theta.i=n2.times.sin .theta.t,
where n1 is the refractive index of a pre-incidence medium, and n2
is the refractive index of a post-incidence medium). Light is
attenuated at the interface due to the refraction as it passes
through the toner layer. The Fresnel transmittance Tn is given by
equation (3): Tn = [ ( n2 .times. .times. cos .times. .times.
.theta. .times. .times. t n1 .times. .times. cos .times. .times.
.theta.I ) .times. ( 2 .times. n1 .times. .times. cos .times.
.times. .theta.I n2 .times. .times. cos .times. .times. .theta.I +
n1 .times. .times. cos .times. .times. .theta. .times. .times. t )
2 + ( n2 .times. .times. cos .times. .times. .theta. .times.
.times. t n1 .times. .times. cos .times. .times. .theta.I ) .times.
( 2 .times. n1 .times. .times. cos .times. .times. .theta.I n1
.times. .times. cos .times. .times. .theta.I + n2 .times. .times.
cos .times. .times. .theta. .times. .times. t ) 2 ] / 2 ( 3 )
##EQU9##
[0222] As light passes through the upper layer portion 34, the
light is attenuated by the upper layer portion 34 before reaching
the lower layer portion 33. The attenuation obeys the Beer-Lambert
law (-logT=a.times.d, where a is the absorption coefficient of a
colorant material layer, d is the thickness of the colorant
material layer, and T is the transmittance). The length of the
optical path in the upper layer portion 34 traveled by the light
before reaching the lower layer portion 33 changes with the
incident light angle. The apparent transmittance Tt' in accordance
with the changes in the length of the optical path is given by
-logTt'=a.times.(d/cos .theta.i). Light attenuation is evaluated in
terms of the apparent transmittance.
[0223] From the above description, the amount of incident light
reaching the lower layer portion 33 is calculated by evaluating the
attenuation of the amount of light from the apparent transmittance
Tt' in accordance with the Fresnel transmittance Tn and the changes
in the length of the optical path. The calculation also takes into
consideration the changes of the incident light angle of the light
to the lower layer portion 33 caused by the refraction. A similar
optical phenomenon occurs when the reflection from the lower layer
portion 33 travels back to the air layer. Therefore, the lower
layer reflection light component Lru is calculated by calculating
from the gonio data of the sample with only the lower layer portion
(paper) measured in S22 for all incident light angles and light
reflection angles with the two refractions and an attenuation of
light (see FIG. 15) taken into consideration. If the incident light
angle .theta.t after the refraction has decimal places, the angle
is interpolated by proration from the preceding and succeeding
angle values. There are no particular limitations on angle
resolution in the process. Here, the resolution is 1.degree.
because the measuring device has a maximum angle resolution of
1.degree.. To calculate the specular reflection light component
more precisely, the angle resolution is preferably 1.degree. or
less.
[0224] Next, the luminance value Lra (L* of CIE 1976 L*a*b*) of the
sample is measured in one certain geometry which contains almost
zero surface reflection light component (step S24). This geometry
is termed a first non-specular reflection geometry. Generally, the
more the geometry differs from specular reflection, the smaller the
surface reflection light component. The first non-specular
reflection geometry selected here therefore preferably has a large
light source incident light angle and includes a light source
incidence position and a light receiving position in close
proximity. For the present embodiment, an exemplary first
non-specular reflection geometry is selected where the light source
incident light angle .theta.i is 45.degree. (.phi.i=0.degree.) and
the light reflection angle .theta.r is -60.degree. (.phi.r
0.degree.).
[0225] Further, in one certain geometry which contains a little
surface reflection light component, the luminance value Lrc (L* of
CIE 1976 L*a*b*) of the sample is measured (step S25). This
geometry is termed a second non-specular reflection geometry. The
second non-specular reflection geometry selected here is preferably
between the first non-specular reflection geometry and the specular
reflection geometry, not very similar to any of the two geometries,
and substantially intermediate between the two. For the present
embodiment, an exemplary second non-specular reflection geometry is
selected where the light source incident light angle .theta.i is
45.degree. (.phi.i=0.degree.) and the light reflection angle
.theta.r is 0.degree. (.phi.r=0.degree.).
[0226] Then, the luminance value Lrb (L* of CIE 1976 L*a*b*) of the
sample is measured in one certain specular reflection geometry
(step S26). This geometry is termed the specular reflection
geometry. The specular reflection geometry selected here is such
that the light source incident light angle is 45.degree.
(.phi.i=0.degree.) and the light reflection angle is 45.degree.
(.phi.r=180.degree.). The present invention is not limited to these
angles.
[0227] Next, the density distribution of the toner image sample is
measured, and its roughness variable op is calculated from the
measured value (step S27). Subsequently, the surface shape of the
sample is measured, and its roughness variable .sigma.s is
calculated from the measured value (step S28). A specific method
for the calculation of the roughness variable .sigma.s of the
surface shape and the roughness variable .sigma.p will be detailed
later.
[0228] Subsequently, the luminance value Lra measured in S24, the
luminance value Lrc measured in S25, and the luminance value Lrb
measured in S26 is subjected to fitting using a Torrance-Sparrow
model and an Oren-Nayar model (step S29). This fitting process is
now detailed in the following.
[0229] Each of Lra, Lrb, and Lrc above is a sum of the surface
reflection light component Lrss, the colorant material particle
reflection light component Lrsp, the diffuse reflection light
component Lrd, and the lower layer reflection light component Lru.
Therefore, the components obtained by subtracting Lru from Lra,
Lrb, or Lrc each correspond to the sum of Lrss, Lrsp, and Lrd (in
other words, the upper layer reflection light component).
[0230] Here, to determine the allocation ratio of the surface
reflection light component, the colorant material particle
reflection light component, and the diffuse reflection light
component in the upper layer reflection light component (in other
words, the sum of Lrss, Lrsp, and Lrd), parameters kss, ksp, and kd
are introduced. Note that kss+ksp+kd=1 (4) In this case, using a
Torrance-Sparrow model and an Oren-Nayar model, the upper layer
reflection light component is given by equation (5):
Lrss+Lrsp+Lrd=kss.times.LrTSs+ksp.times.LrTSp+kd.times.LrON (5),
where LrTSs is a Torrance-Sparrow model calculated value for the
surface reflection light component Lrss, LrTSp is a
Torrance-Sparrow model calculated value for the colorant material
particle reflection light component Lrsp, and LrON is an Oren-Nayar
model calculated value for the diffuse reflection light component
Lrd.
[0231] The roughness variable .sigma. for the Torrance-Sparrow
model used in the process is a parameter defining the range of the
reflection light component in the physical model. Therefore, for
the surface reflection light component Lrss, the roughness variable
.sigma.s of the surface shape obtained in S28 is employed. For the
colorant material particle reflection light component Lrsp, the
roughness variable .sigma.p of the density distribution obtained in
S27 is employed. In addition, the roughness variable .sigma.p of
the density distribution obtained in S27 is employed as the
roughness variable .sigma. for the Oren-Nayar model. E0 (see FIG.
5) is irradiance incident to the sample. Here, since the measured
value space is CIE 1976 L*a*b* space, and L* is employed,
E0=100.pi.. F is set to 1 to obtain surface reflection in the
specular reflection geometry.
[0232] Then, Lru in the first non-specular geometry, calculated in
step S23, is subtracted from the measured Lra. The remaining
component (in other words, Lra-Lru) is substituted to the left side
of equation (5). .theta.i, .theta.r, .phi.i, and .phi.r
corresponding to the first non-specular geometry are substituted to
model equations on the right side to generate equation (6).
[0233] Similarly, Lru in the second non-specular geometry,
calculated in step S23, is subtracted from the measured Lrc. The
remaining component (in other words, Lrc-Lru) is substituted to the
left side of equation (5). .theta.i, .theta.r, .phi.i, and .phi.r
corresponding to the second non-specular geometry are substituted
to model equations on the right side to generate equation (7).
[0234] Further, Lru in the specular geometry, calculated in step
S23, is subtracted from the measured Lrb. The remaining component
(in other words, Lrb-Lru) is substituted to the left side of
equation (5). .theta.i, .theta.r, .phi.i, and .phi.r corresponding
to the specular geometry are substituted to model equations on the
right side to generate equation (8).
[0235] Then, by solving equations (6) to (8), and (4), the unknown
parameter .rho. in the Oren-Nayar model and the parameter kss, ksp,
kd indicating the allocation ratio are determined (step S29). The
reflectance .rho. of the small plane on the sample surface is never
negative in the physical model; only positive values are employed
(.rho.>0).
[0236] The parameter .rho. in Oren-Nayar model and the parameters
kss, ksp, kd indicating the allocation ratio, which are all
determined as above, are used to calculate the surface reflection
light component Lrss, the colorant material particle reflection
light component Lrsp, and the diffuse reflection light component
Lrd in each geometry (step S30).
[0237] To describe it in more detail, Lrss=kss.times.LrTSs
Lrsp=ksp.times.LrTSp Lrd=kd.times.LrON By substituting .theta.i,
.theta.r, .phi.i, and .phi.r corresponding to each geometry to the
model calculation equations in these equations, the upper layer
surface reflection light component Lrss, the colorant material
particle reflection light component Lrsp, and the diffuse
reflection light component Lrd in each geometry are calculated.
[0238] Then, the lower layer reflection light component Lru
obtained in step 23 and the upper layer surface reflection light
component Lrss, the colorant material particle reflection light
component Lrsp, and the diffuse reflection light component Lrd
obtained in step S30, all in the same geometry, are added up to
obtain the specular reflection light component (amount of specular
reflection light) Lr. The specular reflection light component Lr is
obtained for each geometry (step S31).
[0239] In embodiment 2 above, Lrss and Lrsp were both approximated
to 0 in the calculation of the diffuse reflection light component
Lrd (step S16). The present embodiment involves no such
approximation. Accordingly, in the present embodiment, the
reflection light components and the amount of the specular
reflection light are obtained more precisely.
[0240] The aforementioned specular gloss simulation method takes
every kind of image (low gloss image, low density image, etc.) into
consideration, and therefore assumes separating a sample on which
measurement is to be made into an upper layer portion and an lower
layer portion. However, special measurement samples (high density,
high gloss samples) may be treated differently. The specular
reflection light component Lr may be calculated using only the
reflection light component from only the upper layer portion (the
surface reflection light component Lrss, the colorant material
particle reflection light component Lrsp, and the diffuse
reflection light component Lrd). This is because in this case, the
lower layer reflection light component Lru is too small to affect
the specular reflection light component Lr.
[0241] In addition, in the present embodiment, to calculate the
specular reflection light component Lr for each geometry in step
S31, the gonio data is measured for each geometry in step S22. This
is however by no means limiting the present invention. For example,
if the specular reflection light component is to be calculated only
for one certain desired geometry, it is sufficient to measure in
step S22 the gonio data for geometries corresponding to the desired
geometry, the first non-specular reflection geometry, the second
non-specular reflection geometry, and the specular reflection
geometry. The "geometries corresponding to the desired geometry,
the first non-specular reflection geometry, the second non-specular
reflection geometry, and the specular reflection geometry" are
those with the refractive index of the upper layer portion 34 taken
into consideration. To describe in more detail, those geometries
are such a reflection angle at which incident light to the light
receiving section reflects from the lower layer portion 33 and such
that the incident light angle at which the beam actually enters the
lower layer portion 33 when the reflection of a beam shone onto the
sample is measured with a light receiving section in the desired
geometry, the first non-specular geometry, the second non-specular
geometry, and the specular geometry. In addition, it is sufficient
in this case to calculate in the reflection light components in a
desired geometry also in steps S30, S31. This is similarly true
with embodiments 1 and 2 above.
[0242] In the aforementioned specular gloss simulation method,
steps S21 to S23 are a lower layer reflection light component
forming step, steps S24 to S30 are an upper layer reflection light
component forming step, and step S31 is a specular reflection light
amount calculating step.
[0243] Next, an arrangement of a specular gloss simulation device
according to the present invention is described below. The specular
gloss simulation device according to the present embodiment
calculates out the specular reflection light component of each
specular reflection geometry by performing the process illustrated
in the flowchart of FIG. 24. From the specular reflection light
components thus obtained, the specular gloss simulation device
simulates the specular gloss. In FIG. 25, an arrangement of a
specular gloss simulation device 400 according to the present
invention is illustrated.
[0244] As illustrated in FIG. 25, the specular gloss simulation
device 400 is provided mainly with a calculating section 401, an
operation input section 402, a storage 403, and a gonio data
measuring section 404.
[0245] The calculating section 401 calculates out a specular
reflection light component from (a) data of refractive index and
transmittance, the variable of the density distribution on the
sample, the variable of the surface coarseness of the sample (which
has been inputted via the operation input section 402) of the upper
portion (toner image) 34, (b) the first non-specular reflection
geometry/the second non-specular reflection geometry/specular
reflection geometry/being designated via the operation input
section 402, and (c) gonio data being measured by the gonio data
measuring section 404.
[0246] The calculating section 401 is provided with a lower layer
reflection light component calculating section (lower layer
reflection light component creating section) 411, an upper layer
reflection light component calculating section (upper layer
reflection light component creating section) 412, and a specular
reflection light component calculating section (specular reflection
light amount calculating section) 414. The lower layer reflection
light component calculating section 411 is used for calculating a
lower layer reflection light components (Lru). The internal
reflection light component creating section 412 is used for
calculating a diffuse reflection light component (Lrd), a surface
reflection light component (Lrss), and a colorant material particle
reflection light component (Lrsp). The specular reflection light
component calculating section (specular reflection light amount
calculating section) 414 is used for calculating a specular
reflection light component (Lr).
[0247] The lower layer reflection light component calculating
section 411 calculates the lower layer reflection light component
(Lru) in each geometry from the above pieces of information and the
gonio data of the lower layer portion only which are inputted via
the operation input section 402, the gonio data being measured by
using the gonio data measuring section 404.
[0248] The specular reflection light component calculating section
414 adds up the reflection light components of the same specular
reflection geometry, which are calculated by using the lower layer
reflection light component calculating section 411 and the upper
layer reflection light component calculating section 412, thereby
to calculate out the specular reflection light component in each
specular reflection geometry. Note that, in the present embodiment,
the specular reflection light component calculating section 414
calculates the specular reflection light component in each
geometry.
[0249] Based on the measured gonio data of the lower layer portion
only in one specular geometry and two non-specular geometries, the
upper layer reflection light component calculating section 412
calculates the diffuse reflection light component (Lrd), the
surface reflection light component (Lrss), and the colorant
material particle reflection light component (Lrsp) of each
geometry. More specifically, the upper layer reflection light
component calculating section 412 includes a shape-parameter
calculating section (parameter calculating section) 415 and a
reflection light component calculating section 416. The
shape-parameter calculating section 415 is used for calculating (i)
unknown parameter .rho. in the Oren-Nayar model, and (ii)
calculates Kss, Ksp, and Kd each of which indicating allocation of
the diffuse reflection light component, the surface reflection
light component, and the colorant material particle reflection
light component, from a measured gonio data in one specular
reflection geometry and two non-specular reflection geometries. The
reflection light component calculating section calculates the
diffuse reflection light component (Lrd), the surface reflection
light component (Lrss), and the colorant material particle
reflection light component (Lrsp) in each geometries, by using the
parameter .rho., Kss, Ksp, and Kd.
[0250] The operation input section 402 is used for inputting
various numerical values necessary for the calculation of the
specular reflection light component, and for displaying a result of
calculation performed by the calculating section 401. The operation
input section 402 includes operation keys 421 for inputting
numerical values and/or the like, and a display section 422 for
displaying items such as information inputted via the operation
keys 421, the result of calculation, and/or the like.
[0251] The storage section 403 is used for storing therein a result
of the measurement performed by the gonio data measuring section
404, and the result of the calculation performed by the calculating
section 401. The storage section 403 is provided with a first
memory 451 (LUT 1) and a second memory 452 (LUT 2). The first
memory 451 is for storing therein gonio data of a sample measured
by the deviation angle measuring section 404, the sample having a
lower layer portion (paper) 33 only. The second memory 452 is for
storing therein each component light component calculated out by
the calculating section 401.
[0252] The gonio data measuring section 404 measures the gonio data
of the sample having the lower portion (paper) 33 only, and the
gonio data of the sample having the two-layered structure, that is,
having the lower layer portion 33 and the upper layer portion
(toner image) 34. The gonio data measuring section 204 has an
angular resolution of 1.degree., by which the gonio data measuring
section 204 is able to measure the gonio data per degree.
[0253] For simulating the specular glossiness by using the specular
gloss simulation device 200, the gonio data of the sample having
the lower portion (paper) 33 only is measured per degree, meanwhile
for the sample having the lower layer portion 33 and the upper
layer portion 34, it is only required to measure the gonio data of
one specular reflection geometry and one non-specular reflection
geometry.
[0254] Next, how to simulate the specular gloss in each specular
reflection geometry of a sample by using the specular gloss
simulation device 400 is described below, referring to FIGS. 24 and
25.
[0255] Firstly, transmittance of an upper layer portion of a sample
(toner image) is measured in advance by using a transmission
density meter (at S1 in FIG. 24). The transmittance is to be
inputted into the specular gloss simulation device 400 in order to
measure the specular gloss component. Transmittance Tt is
calculated out from Equation Tt=10 (-Dt), where Dt is a
transmission density of only the upper layer portion. The
transmission density is worked out by obtaining a difference
between transmission density of the sample on which the toner image
is formed (i.e., the sample having the lower layer portion 33 and
the upper layer portion 34) and that of the sample having the lower
layer portion (paper) 33 only. A transmission density meter is used
to measure the transmission density of the sample on which the
toner image is formed (i.e., the sample having the lower layer
portion 33 and the upper layer portion 34) and that of the sample
having the lower layer portion (paper) 33 only. The measurement of
the transmission density may be carried out with a X-rite model 820
transmission densitometer made by X-rite Inc.
[0256] The transmittance of the upper layer portion 34 is measured
in S21 of the flowchart of FIG. 24. When using the specular gloss
simulation device 400 of the present invention for evaluating the
specular gloss, the transmittance is measured in advance by using a
separate device, and the transmittance is inputted via the
operation input section 402.
[0257] Next, a shape of the toner layer surface is measured, by
using a shape-measuring microscope VK-9500(manufactured by KEYENCE
corp.) and a variable of roughness of a surface of a toner layer is
calculated based on height information (data regarding Z-axis
direction, where a plane of the sample is an X,Y plane) obtained
from the measurement. Slope of a microscopic surface of the toner
layer surface is calculated based on the height information of an
adjacent picture element. Then, after the slope of the microscopic
surface is plotted in a histogram, a standard deviation of the
slope of the microscopic surface is calculated within a range of
2.sigma. (95.5% of the data) thereby to obtain the variable
.sigma.s of roughness of the surface of the colorant material
layer.
[0258] Meanwhile, a transmission image for the sample is obtained
by using a CCD camera CS-3910 (manufactured by Tokyo Electronic
Industry) and a transmission-use light source whose amount of light
output is 200 W, and the variable of density distribution is
calculated from the obtained transmission image data. The sample is
placed between the CCD camera and the transmission-use light
source. In other words, where the sample is X, Y plane, the CCD
camera and the transmission-use light source are placed in the
Z-direction. Then, the transmission image is obtained. Density of
the picture elements of thus obtained transmission image is plotted
in the histogram. Then, a standard deviation of transmission
density is calculated within a range of 2.sigma. (95.5% of the data
thereby to obtain the variable .sigma.p of density
distribution.
[0259] The variable .sigma.p of the density distribution and the
variable .sigma.s of roughness of the surface shape of the sample
are respectively measured in S27 and S28 of the flowchart of FIG.
24. When using the specular gloss simulation device 400 of the
present invention for evaluating the specular gloss, the variables
are measured in advance by using a separate device, and these
variables are inputted at the same time the transmittance and the
refractive index are inputted.
[0260] Next, the transmittance the variables .sigma.p and .sigma.s
and the refractive index of the upper portion 34 of the sample thus
measured by the above methods are inputted via the operation keys
421 of the operation input section 402. FIG. 26 illustrates an
example of a data input screen displayed on the display section 422
of the specular gloss simulation device 400. On the data input
screen illustrated in FIG. 27, an input item R20 for the refractive
index of the upper portion of the sample to be measured and an
input item R21 for transmittance (Tt) of the sample to be measured,
an input item R22 for the variable of the roughness of the surface
shape of the sample to be measured, and an input item R23 for the
variable of density distribution of the sample to be measured are
displayed. Further, an OK key R24, and a cancel key. R25 are
displayed on the data input screen illustrated in FIG. 27, which
are touch-panel keys. Via the operation keys 421, the
transmittance, the refractive index, and the variables up and as
thus obtained by the above methods are inputted respectively into
the input items R21 to R23 on the display section 422. If the
cancel key R25 is pressed on this data input screen, a measurement
mode is terminated with the data input screen inactivated.
[0261] Then, a base material made of the same material as that of
the base material of the sample to be measured (i.e., the sample
having the lower layer portion) is put in the gonio data measuring
section 404 of the specular gloss simulation device 400, then the
OK key 24 is pressed. In this way, the gonio data measuring section
404 measures the gonio data (CIE 1976*a*b*L*) of the sample having
only the lower portion (at S22 in FIG. 24). The gonio data thus
measured is stored in the first memory 451 of the storage section
403.
[0262] As the gonio data measuring section 404, a gonio-photo
spectrometer GSP-2S (made by Murakami Color Research Laboratory)
may be used, for example. Also, in the gonio data measurement in
the case of a sample only having the lower layer portion, the angle
resolution of the incident light angles and light reflection angles
are 1.degree.. For this reason, the first memory 451 stores the
gonio data values which are measured in increments of 1.degree. of
the incident light angle and the light reflection angle. In the
first memory 451, the gonio data values are associated with the
corresponding incident light angles and light reflection
angles.
[0263] Subsequently, based on the aforesaid refraction theory and
attenuation theory, the lower layer reflection light component
calculating section 411 calculates the lower layer reflection light
components (Lru) of all geometries (the resolution is 1.degree., in
the present example), in reference to (i) the refractive index and
transmittance of the upper layer portion, which are supplied from
the operation input section 402 and (ii) the gonio data values
stored in the first memory 451 (S23 in FIG. 8). The lower layer
reflection light components (Lru) thus calculated are stored in the
second memory 452 in the storage section 403.
[0264] Then the first non-specular reflection geometry is selected,
and the incident light angle and light reflection angle of the
first non-specular reflection geometry are supplied from the
operation input section 402. As a result, the gonio data measuring
section 404 measures the gonio data Lra of the first non-specular
reflection geometry (S24 in FIG. 8). Subsequently, the second
non-specular reflection geometry is selected, the incident light
angle and light reflection angle of the second non-specular
reflection geometry are supplied from the operation input section
402, and the gonio data Lru of the second non-specular reflection
geometry is measured (S25 in FIG. 24). Then the specular reflection
geometry is further selected, the incident light angle and the
light reflection angle of this specular reflection geometry are
supplied from the operation input section 402, and the gonio data
Lrb of the specular reflection geometry is measured (S26 in FIG.
24).
[0265] FIG. 27 shows an example of a data input screen displayed on
the display section 422 in order to input the selected first
non-specular reflection geometry, second non-specular reflection
geometry, and specular reflection geometry. It is noted that
although the first non-specular reflection geometry, second
non-specular geometry, and specular reflection geometry are
simultaneously input in the case above, the present invention is
not necessarily limited to this arrangement. The data input screen
shown in FIG. 27 displays: an input item R30 and an input item R31
for the incident light angle and the light reflection angle of the
second non-specular reflection geometry. respectively; an input
item R37 and an input item R38 for the incident light angle and the
light reflection angle of the first non-specular reflection
geometry, respectively; an input item R32 and an input item R33 for
the incident light angle and the light reflection angle of the
specular reflection geometry, respectively; an OK button R34; a
cancel button R35; and a back button R36. In the present case, the
OK button R34, cancel button R35, and back button R36 are
touch-panel type. If the cancel button R35 is pushed, the data
input screen finishes and the measurement mode is compulsorily
terminated. If the back button R36 is pushed, the data input screen
shown in FIG. 27 is shown again.
[0266] The incident light angles and the light reflection angles of
the first and second non-specular reflection geometries must be
individually specified. However, since the incident light angle is
equal to the light reflection angle in the specular reflection
geometry, the value of the incident light angle input in the input
item R32 for the incident light angle is automatically displayed
and set in the item R33 for the light reflection angle.
[0267] After the first non-specular reflection geometry, second
non-specular reflection geometry, and specular reflection geometry
are input as above and the sample in which a toner image is formed
is set in the gonio data measuring section 404, the OK button R34
is pushed. In response to this, the gonio data values Lra, Lrb, and
Lrc of each of the aforesaid geometries are measured.
[0268] The gonio data values Lra, Lrb, and Lrc of each geometry,
which have been measured, are supplied to the upper layer
reflection light component calculating section 412. In accordance
with the gonio data values Lra, Lrb, and Lrc thus supplied, the
upper layer reflection light component calculating section 412
performs the fitting with the Oren-Nayar model and the
Torrance-Sparrow model, and calculates the diffuse reflection light
components (Lrd), the surface reflection light components (Lrs),
and the reflection light components (Lrsp) of the colorant material
particles, of all geometries (Steps S29 and S30).
[0269] The following more specifically describes the process above.
First, the gonio data value measured by the gonio data measuring
section 404 is supplied to the configuration parameter calculating
section 415 of the upper layer reflection light component
calculating section 412. Also, the configuration parameter
calculating section 415 obtains, from the second memory 452, the
lower layer reflection light components Lru of the first
non-specular reflection geometry, the second non-specular
reflection geometry, and the specular reflection geometry. From the
operation input section 402, roughness parameters .sigma.p and
.sigma.s are supplied to the configuration parameter calculating
section 415. The configuration parameter calculating section 415
then performs the fitting in accordance with the aforesaid method,
so as to calculate (i) a parameter .rho. indicating the reflectance
on a microscopic surface in the case of the Oren-Nayar model, and
(ii) parameters kss, ksp, and kd indicating the distribution ratio
among the diffuse reflection light component, the surface
reflection light component, and the reflection light component of
the colorant material particles (Step S29).
[0270] The calculated values .rho., kss, ksp, and kd are supplied
from the configuration parameter calculating section 415 to the
reflection light component calculating section 416. By the
aforesaid method, the reflection light component calculating
section 416 calculates, for all geometries, the diffuse reflection
light components (Lrd), the surface reflection light components
(Lrs), and the reflection light components (Lrsp) of the colorant
material particles (Step S30). Then the reflection light component
calculating section 416 stores these reflection light components in
the second memory 452. The reflection light components stored in
the second memory 452 are associated with the corresponding
geometries.
[0271] Subsequently, the specular reflection light component
calculating section 414 obtains, for each geometry, the lower layer
reflection light component (Lru), the diffuse reflection light
component (Lrd), the surface reflection light component (Lrs) and
the reflection light component (Lrsp) of the colorant material
particles, from the second memory 452. The specular reflection
light component calculating section 414 then adds up these
components so as to calculate the specular reflection light
component (Lr) (Step S31). In the present embodiment, the specular
reflection light component (Lr) is calculated for each geometry.
The calculated specular reflection light components (Lr) of all
geometries are supplied to the display section 422 of the operation
input section 402, letting the user see the result on the display
section 422. FIG. 28 shows an example of the measurement result
displayed on the display section 422.
[0272] As shown in FIG. 28, after the calculation of the specular
reflection light components Lr, the display section 422 displays: a
graph R40 of the specular reflection light components Lr; an input
item R41 for the specular reflection geometry; a calculation result
R42 of the specular reflection light component Lr of the geometry
input in the input item R41; an input item R46 for a gloss
threshold; a calculation result R47 of the specular reflection
geometry indicating the threshold input in the input item R46; an
OK button R43; a cancel button R44; and a back button R45. The
graph R40 of the specular reflection light components Lr shows the
list of all specular reflection light components Lr, in a case
where the incident light angles are in the range of 10.degree. and
80.degree.. It is therefore possible to see what extent a sample
specular reflection light component is dependent on the angle. The
results shown in the graph R40 are calculated in the specular
reflection light component calculating section 414 by adding up the
lower layer reflection light components Lru, diffuse reflection
light components Lrd, surface reflection light components Lrss, and
reflection light components Lrsp of the colorant material particle,
of all specular reflection geometries stored in the second memory
452.
[0273] In the specular gloss simulation device 400, an arbitrary
angle is input in the input item R41 of the specular reflection
geometry shown in FIG. 28, and the OK button R43 is pushed. With
this, the value of the specular reflection light component of the
angle thus input is obtained. The calculated value of this case is
equal to a point on the graph R40 of the specular reflection light
components Lr.
[0274] In the meanwhile, a desired specular reflection light
component (corresponding to the gloss) is inputted in the input
item R46 for the gloss threshold and the OK button R43 is pushed.
With this, an angle corresponding to the specular reflection light
component thus input is displayed as the calculation result R47.
The calculation result proves that angles corresponding to the
specular reflection light components higher than the component thus
inputted are greater than the displayed angle. In other words, the
specular gloss simulation device 400 of the present embodiment
makes it possible to calculate the specular reflection light
components of all specular reflection geometries. Therefore, by
varying the specular reflection geometry (incident and light
reflection angles), it is possible to confirm in which case the
specular reflection light component exceeds a predetermined value.
This can be effectively used as a novel valuation standard for the
gloss.
[0275] If the cancel button R44 in the result screen shown in FIG.
28 is pushed, the result screen finishes and the measurement mode
is compulsorily terminated. If the back button R45 is pushed, the
data input screen shown in FIG. 27 is shown again.
[0276] In a case where the specular reflection light component
simulated as above is converted to the gloss in conformity to
Japanese Industrial Standards, the gloss is figured out in such a
manner that a relative value is calculated based on a value in the
case of a standard plate (glass plate with a refractive index of
1.567) specified as a standard sample.
[0277] The specular gloss simulation device 400 may be realized
using a computer system. The computer system may be similar to the
computer system 300 (see FIG. 12) of Embodiment 1.
[0278] As in the case of Embodiment 1, the processing steps
performed by the calculating section 401 of the specular gloss
simulation device 400 of the present embodiment and the processing
steps performed by the lower layer reflection light component
calculating section 411, the upper layer reflection light component
calculating section 412, the specular reflection light component
calculating section 414 in the calculating section 401 are realized
by causing computing means such as a CPU to execute a program
stored in storage means such as ROM (Read Only Memory) or RAM, so
as to control the input means such as a keyboard, output means such
as a display, or a communication means such as an interface
circuit. On this account, the functions and processes of the
specular gloss simulation device 400 can be realized only by
causing the computer having the aforesaid means to read a storage
medium storing the program and execute the program. If the program
is stored in a removable storage medium, the aforesaid functions
and processes can be realized on any computer.
[0279] The invention being thus described, it will be obvious that
the same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modifications as would be obvious to one skilled in
the art intended to be included within the scope of the following
claims.
EXAMPLE 1
[0280] In the present example, a sample was prepared by using a
high concentration toner for forming a colorant material layer on a
base material which was paper, and specular glossiness of the
sample was evaluated by using the specular gloss simulation device
100 of Embodiment 1.
[0281] First, values were entered as follows in respective input
items on a data input screen illustrated in FIG. 9. Namely, "1.55"
was entered in a refractive index input item 20, and "6.4%" was
entered in a transmission-factor input item 21. Meanwhile, a sample
which was paper having no colorant material layer was set at a
gonio data measuring section 104, and then gonio data was measured.
Then, values were entered as follows in respective input items on a
data input screen illustrated in FIG. 10. Namely, for a
non-specular reflection geometry, "45.degree." was entered in an
incident light angle input item 30, and "-60.degree." was entered
in a reflection light angle input item 31. For a specular
reflection geometry, "45.degree." was entered in an incident light
angle input item 32. Meanwhile, the sample having the toner image
was set at a gonio data measuring section 104, and then gonio data
was measured.
[0282] FIG. 20(a) shows a graph 40 of FIG. 11 which was displayed
as a result of the measurement. In the graph illustrated in FIG.
20(a), the horizontal axis indicates the incident light angle and
the reflection light angle in the specular reflection geometry, and
a vertical axis indicates a luminance value (L* of CIE1976L*a*b*)
of a specular reflection light component. In the present example, a
gonio-photo spectrometer was used so as to carry out, with respect
to the same sample, an actual measurement of the geometric specular
reflection light component in each specular reflection geometry.
Then, the result of the actual measurement and the result of the
foregoing measurement were compared with each other. In the graph
of FIG. 20(a), the solid line indicates the result obtained from
the calculation using the technique of the present invention, and
the dotted line indicates the result obtained from the actual
measurement. As indicated in the figure, the two results exhibited
substantially identical behaviors. This proves that the technique
of the present invention is highly accurate.
EXAMPLE 2
[0283] In the present example, a sample was prepared by using a low
concentration toner for forming a colorant material layer on a base
material which was paper, and specular glossiness of the sample was
evaluated by using the specular gloss simulation device 100 of
Embodiment 1.
[0284] First, values were entered as follows in respective input
items on a data input screen illustrated in FIG. 9. Namely, "1.55"
was entered in a refractive index input item 20, and "15%" was
entered in a transmission-factor input item 21. Meanwhile, a sample
which was paper having no colorant material layer was set at a
gonio data measuring section 104, and then gonio data was measured.
Then, values were entered as follows in respective input items on a
data input screen illustrated in FIG. 10. Namely, for a
non-specular reflection geometry, "45.degree." was entered in an
incident light angle input item 30, and "-60.degree." was entered
in a reflection light angle input item 31. For a specular
reflection geometry, "45.degree." was entered in an incident light
angle input item 32. Meanwhile, the sample having the toner image
was set at a gonio data measuring section 104, and then gonio data
was measured.
[0285] FIG. 20(b) shows a graph 40 of FIG. 11 which was displayed
as a result of the measurement. In the graph illustrated in FIG.
20(b), the horizontal axis indicates the incident light angle and
the reflection light angle in the specular reflection geometry, and
a vertical axis indicates a luminance value (L* of CIE1976L*a*b*)
of a specular reflection light component. In the present example, a
gonio-photo spectrometer was used so as to carry out, with respect
to the same sample, an actual measurement of the geometric specular
reflection light component in each specular reflection geometry.
Then, the result of the actual measurement and the result of the
foregoing measurement were compared with each other. In the graph
of FIG. 20(b), the solid line indicates the result obtained from
the calculation using the technique of the present invention, and
the dotted line indicates the result obtained from the actual
measurement. As indicated in the figure, the two results exhibited
substantially identical behaviors. This proves that the technique
of the present invention is highly accurate, even if an influence
from a luminance component of reflection from paper increases due
to decrease in a toner concentration.
EXAMPLE 3
[0286] In the present example, paper of 67 g/m.sup.2 or 128
g/m.sup.2 is used as a base material. On this base material, a
colorant material layer was formed by using a high concentration
toner, thereby preparing a sample. Then, specular glossiness of the
sample was evaluated by using the specular gloss simulation device
100 of Embodiment 1.
[0287] The evaluation of the specular glossiness was carried out as
in Examples 1 and 2, except in that, in the transmission-factor
input item 21 illustrated in FIG. 9, "7.5%" was entered when using
the paper of 67 g/m.sup.2, and "7.2%" was entered when using the
paper of 128 g/m.sup.2. FIG. 21(a) shows a result obtained in the
case of using the paper of 67 g/m.sup.2, and FIG. 21(b) shows a
result obtained in the case of using the paper of 128 g/m.sup.2.
Note that, as in the foregoing examples, a gonio-photo spectrometer
was also used in the present example, so as to carry out, with
respect to the same sample, an actual measurement of the geometric
specular reflection light component in each specular reflection
geometry. Then, the result of the actual measurement and the result
of the foregoing measurement were compared with each other.
[0288] As indicated in the figure, the calculation result and the
actually-measured value were substantially identical to each other
at all of the angles in the present example too. Further, it is
found that an angle change causes a less amount of change in the
luminance value, than a case of using paper. This is because a
greater roughness of a toner layer surface causes wider scattering
of a surface reflection light component Lrs, which consequently
increases influence from an internal reflection light component
Lri. As described, it is found that the technique of the present
invention is highly accurate, even if the influence from the
internal reflection light component Lri increases.
EXAMPLE 4
[0289] In the present example, a sample was prepared by using a
high concentration toner for forming a colorant material layer on a
base material which was paper, and specular glossiness of the
sample was evaluated by using the specular gloss simulation device
200 of Embodiment 2.
[0290] First, values were entered as follows in respective input
items on a data input screen illustrated in FIG. 17. Namely, "1.55"
was entered in a refractive index input item 50, "6.4%" was entered
in a transmission-factor input item 51, "0.205" was entered in a
surface coarseness input item 52, and "0.037" was entered in a
density distribution input item 53. Meanwhile, a sample which was
paper having no colorant material layer was set at a gonio data
measuring section 204, and then gonio data was measured.
[0291] Then, values were entered as follows in respective input
items on a data input screen illustrated in FIG. 18. Namely, for a
non-specular reflection geometry, "45.degree." was entered in an
incident light angle input item 60, and "-60.degree." was entered
in a reflection light angle input item 61. For a specular
reflection geometry, "45.degree." was entered in an incident light
angle input item 62. Meanwhile, the sample having the toner image
was set at a gonio data measuring section 204, and then gonio data
was measured.
[0292] FIG. 22(a) shows a graph 70 of FIG. 19 which was displayed
as a result of the measurement. In the graph illustrated in FIG.
22(a), the horizontal axis indicates the incident light angle and
the reflection light angle in the specular reflection geometry, and
a vertical axis indicates a luminance value (L* of CIE1976L*a*b*)
of a specular reflection light component. In the present example, a
gonio-photo spectrometer was used so as to carry out, with respect
to the same sample, an actual measurement of the geometric specular
reflection light component in each specular reflection geometry.
Then, the result of the actual measurement and the result of the
foregoing measurement were compared with each other. In the graph
of FIG. 22(a), the solid line indicates the result obtained from
the calculation using the technique of the present invention, and
the dotted line indicates the result obtained from the actual
measurement. As indicated in the figure, the two results exhibited
substantially identical behaviors. This proves that the technique
of the present invention is highly accurate.
[0293] By comparing FIG. 20(a) and FIG. 22(a), it becomes apparent
that the values calculated out in the present example are closer to
the actually measured values than those calculated in Example 1 in
which the specular gloss simulation device 100 of Embodiment 1 was
used for evaluating the specular glossiness under the same
conditions. In short, it is confirmed that the technique of the
present example is more accurate than the technique of Example
1.
EXAMPLE 5
[0294] In the present example, a sample was prepared by using a low
concentration toner for forming a colorant material layer on a base
material which was paper, and specular glossiness of the sample was
evaluated by using the specular gloss simulation device 200 of
Embodiment 2.
[0295] First, values were entered as follows in respective input
items on a data input screen illustrated in FIG. 17. Namely, "1.55"
was entered in a refractive index input item 50, "15%" was entered
in a transmission-factor input item 51, "0.222" was entered in a
surface coarseness input item 52, and "0.047" was entered in a
density distribution input item 53. Meanwhile, a sample which was
paper having no colorant material layer was set at a gonio data
measuring section 204, and then gonio data was measured.
[0296] Then, values were entered as follows in respective input
items on a data input screen illustrated in FIG. 18. Namely, for a
non-specular reflection geometry, "45.degree." was entered in an
incident light angle input item 60, and "-60.degree." was entered
in a reflection light angle input item 61. For a specular
reflection geometry, "45.degree." was entered in an incident light
angle input item 62. Meanwhile, the sample having the toner image
was set at a gonio data measuring section 204, and then gonio data
was measured.
[0297] FIG. 22(b) shows a graph 70 of FIG. 19 which was displayed
as a result of the measurement. In the graph illustrated in FIG.
22(b), the horizontal axis indicates the incident light angle and
the reflection light angle in the specular reflection geometry, and
a vertical axis indicates a luminance value (L* of CIE1976L*a*b*)
of a specular reflection light component. In the present example, a
gonio-photo spectrometer was used so as to carry out, with respect
to the same sample, an actual measurement of the geometric specular
reflection light component in each specular reflection geometry.
Then, the result of the actual measurement and the result of the
foregoing measurement were compared with each other. In the graph
of FIG. 22(b), the solid line indicates the result obtained from
the calculation using the technique of the present invention, and
the dotted line indicates the result obtained from the actual
measurement. As indicated in the figure, the two results exhibited
substantially identical behaviors. This proves that the technique
of the present invention is highly accurate, even if an influence
from a luminance component of reflection from paper increases due
to decrease in a toner concentration.
[0298] By comparing FIG. 20(b) and FIG. 22(b), it becomes apparent
that the values calculated out in the present example are closer to
the actually measured values than those calculated in Example 2 in
which the specular gloss simulation device 100 of Embodiment 1 was
used for evaluating the specular glossiness under the same
conditions. In short, it is confirmed that the technique of the
present example is more accurate than the technique of Example
2.
EXAMPLE 6
[0299] In the present example, paper of 67 g/m.sup.2 or 128
g/m.sup.2 is used as a base material. On this base material, a
colorant material layer was formed by using a high concentration
toner, thereby preparing a sample. Then, specular glossiness of the
sample was evaluated by using the specular gloss simulation device
200 of Embodiment 2.
[0300] The evaluation of the specular glossiness was carried out as
in Examples 4 and 5, except in that, in the transmission-factor
input item 51 illustrated in FIG. 17, "7.5%" was entered when using
the paper of 67 g/m.sup.2, and "7.2%" was entered when using the
paper of 128 g/m.sup.2. FIG. 23(a) shows a result obtained in the
case of using the paper of 67 g/m.sup.2, and FIG. 23(b) shows a
result obtained in the case of using the paper of 128 g/m.sup.2.
Note that, as in the foregoing examples, a gonio-photo spectrometer
was also used in the present example, so as to carry out, with
respect to the same sample, an actual measurement of the geometric
specular reflection light component in each specular reflection
geometry. Then, the result of the actual measurement and the result
of the foregoing measurement were compared with each other.
[0301] As indicated in the figure, the calculation result and the
actually-measured value were substantially identical to each other
at all of the angles in the present example too. Further, it is
found that an angle change causes a less amount of change in the
luminance value, than a case of using paper. This is because a
greater roughness of a toner layer surface causes wider scattering
of a surface reflection light component Lrss and wider scattering
of a reflection light component Lrsp from colorant material
particle, which consequently increases an influence from a diffuse
reflection light component Lrd. As described, it is found that the
technique of the present invention is highly accurate, even if the
influence from the diffuse reflection light component Lrd
increases.
[0302] By comparing FIG. 21 and FIG. 23, it becomes apparent that
the values calculated out in the present example are closer to the
actually measured values than those calculated in Example 3 in
which the specular gloss simulation device 100 of Embodiment 1 was
used for evaluating the specular glossiness under the same
conditions. In short, it is confirmed that the technique of the
present example is more accurate than the technique of Example
3.
EXAMPLE 7
[0303] In the present example, a sample was prepared by using a
high concentration toner for forming a colorant material layer on a
base material which was paper, and specular glossiness of the
sample was evaluated by using the specular gloss simulation device
400 of Embodiment 3.
[0304] First, values were entered as follows in respective input
items on a data input screen illustrated in FIG. 17. Namely, "1.55"
was entered in a refractive index input item R20, "6.4%" was
entered in a transmission-factor input item R21, "0.205" was
entered in a surface coarseness input item R22, and "0.037" was
entered in a density distribution input item R23. Meanwhile, a
sample which was paper having no colorant material layer was set at
a gonio data measuring section 404, and then gonio data was
measured.
[0305] Then, values were entered as follows in respective input
items on a data input screen illustrated in FIG. 27. Namely, for a
first non-specular reflection geometry, "45.degree." was entered in
an incident light angle input item R30, and "-60.degree." was
entered in a reflection light angle input item R31. For a second
non-specular reflection geometry, "45.degree." was entered in an
incident light angle input item R37, and "0.degree." was entered in
a reflection light angle input item R38. For a specular reflection
geometry, "45.degree." was entered in an incident light angle input
item R32. Meanwhile, the sample having the toner image was set at a
gonio data measuring section 404, and then gonio data was
measured.
[0306] FIG. 29(a) shows a graph R40 of FIG. 28 which was displayed
as a result of the measurement. FIG. 29(a) shows a result obtained
in a case of using a high concentration toner sample. In the graph
illustrated in FIG. 29(a), the horizontal axis indicates the
incident light angle and the reflection light angle in the specular
reflection geometry, and a vertical axis indicates a luminance
value (L* of CIE1976L*a*b*) of a specular reflection light
component. In the present example, a gonio-photo spectrometer was
used so as to carry out, with respect to the same sample, an actual
measurement of the geometric specular reflection light component in
each specular reflection geometry. Then, the result of the actual
measurement and the result of the foregoing measurement were
compared with each other. In the graph of FIG. 29(a), the solid
line indicates the result obtained from the calculation using the
technique of the present invention, and the dotted line indicates
the result obtained from the actual measurement. As indicated in
the figure, the two results exhibited substantially identical
behaviors. This proves that the technique of the present invention
is highly accurate.
EXAMPLE 8
[0307] In the present example, a sample was prepared by using a low
concentration toner for forming a colorant material layer on a base
material which was paper, and specular glossiness of the sample was
evaluated by using the specular gloss simulation device 400 of
Embodiment 3.
[0308] First, values were entered as follows in respective input
items on a data input screen illustrated in FIG. 26. Namely, "1.55"
was entered in a refractive index input item R20, "15%" was entered
in a transmission-factor input item R21, "0.222" was entered in a
surface coarseness input item R22, and "0.047" was entered in a
density distribution input item R23. Meanwhile, a sample which was
paper having no colorant material layer was set at a gonio data
measuring section 404, and then gonio data was measured.
[0309] Then, values were entered as follows in respective input
items on a data input screen illustrated in FIG. 27. Namely, for a
first non-specular reflection geometry, "45.degree." was entered in
an incident light angle input item R30, and "-60.degree." was
entered in a reflection light angle input item R31. For a second
non-specular reflection geometry, "45.degree." was entered in an
incident light angle input item R37, and "0.degree." was entered in
a reflection light angle input item R38. For a specular reflection
geometry, "45.degree." was entered in an incident light angle input
item R32. Meanwhile, the sample having the toner image was set at a
gonio data measuring section 404, and then gonio data was
measured.
[0310] FIG. 29(b) shows a graph R40 of FIG. 28 which was displayed
as a result of the measurement. FIG. 29(b) shows a result obtained
in a case of using a toner sample whose concentration is lower than
that used in Example 7. In the graph illustrated in FIG. 29(b), the
horizontal axis indicates the incident light angle and the
reflection light angle in the specular reflection geometry, and a
vertical axis indicates a luminance value (L* of CIE1976L*a*b*) of
a specular reflection light component. In the present example, a
gonio-photo spectrometer was used so as to carry out, with respect
to the same sample, an actual measurement of the geometric specular
reflection light component in each specular reflection geometry.
Then, the result of the actual measurement and the result of the
foregoing measurement were compared with each other. In the graph
of FIG. 29(b), the solid line indicates the result obtained from
the calculation using the technique of the present invention, and
the dotted line indicates the result obtained from the actual
measurement. As indicated in the figure, the two results exhibited
substantially identical behaviors. This proves that the technique
of the present invention is highly accurate, even if an influence
from a luminance component of reflection from paper increases due
to decrease in a toner concentration.
EXAMPLE 9
[0311] In the present example, paper of 67 g/m.sup.2 or 128
g/m.sup.2 is used as a base material. On this base material, a
colorant material layer was formed by using a high concentration
toner, thereby preparing a sample. Then, specular glossiness of the
sample was evaluated by using the specular gloss simulation device
400 of Embodiment 3.
[0312] The evaluation of the specular glossiness was carried out as
in Examples 7 and 8, except in that, in the transmission-factor
input item R21 illustrated in FIG. 26, "7.5%" was entered when
using the paper of 67 g/m.sup.2, and "7.2%" was entered when using
the paper of 128 g/m.sup.2. FIG. 30(a) shows a result obtained in
the case of using the paper of 67 g/m.sup.2, and FIG. 30(b) shows a
result obtained in the case of using the paper of 128 g/m.sup.2.
Note that, as in the foregoing examples, a gonio-photo spectrometer
was also used in the present example, so as to carry out, with
respect to the same sample, an actual measurement of the geometric
specular reflection light component in each specular reflection
geometry. Then, the result of the actual measurement and the result
of the foregoing measurement were compared with each other.
[0313] As indicated in the figure, the calculation result and the
actually-measured value were substantially identical to each other
at all of the angles in the present example too. Further, it is
found that an angle change causes a less amount of change in the
luminance value, than a case of using paper. This is because a
greater roughness of a toner layer surface causes wider scattering
of a surface reflection light component Lrss and wider scattering
of a reflection light component Lrsp from colorant material
particle, which consequently increases an influence from a diffuse
reflection light component Lrd. As described, it is found that the
technique of the present invention is highly accurate, even if the
influence from the diffuse reflection light component Lrd
increases.
OTHER
[0314] According to the present invention, it is possible to
accurately evaluate specular gloss of an image formed in various
ways. Therefore, the present invention can be applied to evaluation
of images in quality.
[0315] As described above, a specular gloss simulating device
according to the present invention for simulating specular gloss by
measuring, in a given geometry, luminance of a sample that has a
base material and a colorant material layer formed on the base
material, and then simulating a specular reflection light amount in
an other geometry from the thus measured luminance, is arranged to
include: a lower layer reflection light component creating section
for calculating a lower layer reflection light component from base
material luminance, where the base material luminance is luminance
of only the base material measured in a plurality of geometries,
and the lower layer reflection light component is a component being
reflected on the base material and transmitting through and out of
the colorant material layer; an internal reflection light component
creating section for measuring luminance of the sample in the given
geometry, and for creating an internal reflection light component
from the measured luminance and the lower layer reflection light
component, where the internal reflection light component is a
component being reflected from an interior of the colorant material
layer; a surface reflection light component creating section for
measuring luminance of the sample in the given geometry, and for
creating a surface reflection light component from the measured
luminance, the lower layer reflection light component, and the
internal reflection light component, where the surface reflection
light component is a component being reflected on a surface of the
colorant material layer; and a specular reflection light amount
calculating section for obtaining a specular reflection light
amount of the sample from the components thus created by the lower
layer reflection light component creating section, internal
reflection light component creating section, and surface reflection
light component creating section.
[0316] With the above arrangement, the simulation of the specular
gloss is carried out by obtaining the specular reflection light
amount of the sample by more effectively using the Bidirectional
Reflectance Distribution Function model, taking the lower layer
reflection light component and the internal reflection light
component, as well as the surface reflection light component, into
consideration. This makes it possible to calculate out the specular
gloss with high accuracy for low-density image sample and low-gloss
image sample for which accurate calculation of the specular gloss
cannot be done with the conventional art.
[0317] The specular gloss simulating device according to the
present invention is preferably arranged such that: the lower layer
reflection light component creating section measures the base
material luminance in the plurality of geometries, and calculates
out the lower layer reflection light component from the thus
measured luminance; the internal reflection light component
creating section measures the luminance of the sample in a
non-specular reflection geometry, calculates out the internal
reflection light component from the thus measured luminance and the
lower layer reflection light component, and simulates an internal
reflection light component in the other geometry by using a
Bidirectional Reflectance Distribution Function model; and the
surface reflection light component creating section measures the
luminance of the sample in a specular reflection geometry,
calculates out the surface reflection light component from the thus
measured luminance, the lower layer reflection light component, and
the internal reflection light component, and simulates the surface
reflection light component in an other specular reflection geometry
than the geometry by using a Bidirectional Reflectance Distribution
Function model.
[0318] The specular gloss simulation device of the present
invention is used for simulating, by using the Bidirectional
Reflectance Distribution Function model, a specular reflection
light amount of a sample in each geometry, the sample having, as a
sample image, the colorant material layer on the base material,
where the base material may be paper, an OHP film or the like, and
the colorant material layer contains toner, pigment ink, dye ink or
the like. From the thus simulated specular reflection light amount,
the specular gloss component of the sample is simulated in the
method according to the present invention.
[0319] In the specular gloss simulating device, not only the
surface reflection light component reflected on the surface of the
colorant material layer, but also the internal reflection light
component reflected from the interior of the colorant material
layer and the lower layer reflection light component reflected on
the base material are taken into consideration. So, the specular
reflection light amount of the sample is calculated from the
surface reflection light component, the internal reflection light
component, and the lower layer reflection light component thus
calculated out.
[0320] Here, the "geometry" is a positional relationship of a light
source, image sample, and a photoreceptor in the measurement of the
reflection light amount from the image sample to evaluate the
specular gloss or the like. More specifically, what is meant by the
term "geometry" is the incident light angle 1 and the reflection
light angle 2.
[0321] Here, the term "incident light angle" is an angle between
(a) a light beam from the light source and being incident on the
sample, and (b) a normal vector of a plane of the sample at a point
at which the light beam is incident on the plane of the sample. The
"reflection light angle" is an angle between a light beam reflected
on the plane of the sample and the normal vector. Therefore, a
"given geometry" has a predetermined incident light angle 1 and a
predetermined reflection light angle 2.
[0322] Moreover, Among given geometries, the "specular reflection
geometry" is a geometry whose incident light angle and the
reflection light angle are for the specular reflection of the
incident light on the sample. The incident light angle 1 and the
reflection light angle 2 (illustrated in FIG. 2) of this geometry
are identical with each other.
[0323] Moreover, Among given geometries, the "non-specular
reflection geometry" is any geometry other than the specular
reflection geometry.
[0324] In the present invention, it is possible to select any
"specular reflection geometry" and "non-specular reflection
geometry" which satisfy the above conditions. In the embodiments,
the non-specular reflection geometry in which the light source
incident light angle qi=45.degree. and the reflection light angle
qr=-60.degree. (see FIG. 5) is selected, while the specular
reflection geometry in which the light source incident light angle
qi=45.degree. and the reflection light angle qr=45.degree. (see
FIG. 5) is selected.
[0325] The "plurality of geometries" for use in the measurement of
the luminance of the base material only for the calculation of the
lower layer reflection light component are geometries varied in the
light source incident light angle and the reflection light angle by
a constant angle. The "plurality of geometries" are so varied that
all positional relationships possible under measurement environment
are included. A specific example of the "plurality of geometries"
is the "each geometry" used in the embodiments in which the
geometries are varied in the light source incident light angle and
the reflection light angle by angular resolution of 1.degree..
[0326] In the present specification, the term "each geometry (or
all geometry)" may encompass any geometry possible under the
measurement environment literally. However, in the present
Specification, this terms "each geometry (or all geometry)" is also
used to mean the "geometries varied in the light source incident
light angle and the reflection light angle by a constant angle". A
specific example of the "each geometry (or all geometry)" is the
geometries varied in the light source incident light angle and the
reflection light angle by angular resolution of 1.degree. to
include all the positional relationships possible under the
measurement environment. Further, the term "each specular
reflection geometry" is geometries among the "each geometry (or all
geometry)", especially.
[0327] In this arrangement, the internal reflection light component
and the surface reflection light component of each geometry are not
actually measured for the calculation of the specular reflection
light amount of the sample. The reflection light component (i.e.,
lower layer reflection light component) from only the lower layer
portion (that is, the base material), which can be actually
measured is measured in the plurality of geometries (i.e., each
geometry) varied in the light source incident light angle and the
reflection light angle at the constant angle. From the thus
measured lower layer reflection light component, the specular
reflection light amount of the sample can be calculated with high
accuracy with this arrangement. Further, with this arrangement, the
simulation of the specular gloss is carried out by obtaining the
specular reflection light amount of the sample by more effectively
using the Bidirectional Reflectance Distribution Function model,
taking the lower layer reflection light component and the internal
reflection light component, as well as the surface reflection light
component, into consideration. This makes it possible to calculate
out the specular gloss with high accuracy for low-density image
sample and low-gloss image sample for which accurate calculation of
the specular gloss cannot be done with the conventional art.
[0328] The specular gloss simulating device may be preferably
arranged such that the Bidirectional Reflectance Distribution
Function model used by the surface reflection light component
creating section for simulating the surface reflection light
component in the other specular reflection geometry is a
Torrance-Sparrow model.
[0329] The Torrance-Sparrow model is on assumption that the light
is scattered anisotropically. With this arrangement, the use of
Torrance-Sparrow model allows accurate simulation of the surface
reflection light component in each specular reflection geometry
from the measurement result obtained in one predetermined specular
reflection geometry. Moreover, the Torrance-Sparrow model is easy
to use because it required a small number of parameters.
[0330] The specular gloss simulating device according to the
present invention may be preferably arranged such that the
Bidirectional Reflectance Distribution Function model used by the
internal reflection light component creating section for simulating
the internal reflection light component in the other geometry is an
Oren-Nayar model.
[0331] The Oren-Nayar model is on assumption that the light is
scattered anisotropically. With this arrangement, the use of
Oren-Nayar model allows accurate simulation of the internal
reflection light component in each geometry from the measurement
result obtained in one predetermined non-specular reflection
geometry. Moreover, the Oren-Nayar model is easy to use because it
required a small number of parameters.
[0332] The specular gloss simulating device according to the
present invention may be preferably arranged such that the lower
layer reflection light component creating section calculates out
the lower layer reflection light component from the measured
luminance of the base material, and transmittance and refractive
index of the colorant material layer.
[0333] This arrangement makes it possible to accurately reproduce
the incident light angle and light amount of the light reaching the
base material portion of the sample, the reflection light amount of
the light reflected from the base material portion with attenuation
due to refraction. Therefore, it becomes possible to calculate out
the reflection light component from the lower layer portion with
higher accuracy.
[0334] The specular gloss simulating device may be arranged such
that the internal reflection light component creating section also
functions as a diffuse reflection light component creating section
for simulating diffuse reflection light component which is a
component being diffused among colorant material particles
contained in the colorant material layer and transmitting out of
the colorant material layer; the internal reflection light
component creating section comprises: a colorant material particle
reflection light component creating section (a) for measuring
luminance of the sample in the specular reflection geometry, (b)
for calculating out a colorant material particle reflection light
component from the thus measured luminance, the lower layer
reflection light component, and the diffuse reflection light
component, and (c) for simulating a colorant material particle
reflection light component in the other geometry by using the
Bidirectional Reflectance Distribution Function model, where the
colorant material particle reflection light component is a
component reflected from the colorant material particles; and a
shape parameter calculating section for deciding a mixing ratio
between the colorant material particle reflection light component
and the surface reflection light component from the results of the
calculations performed by the surface reflection light component
creating section and the colorant material particle reflection
light component creating section, and the thus measured luminance
of the sample in the specular reflection geometry, and the specular
reflection light amount calculating section obtains the specular
reflection light amount by adding up the components thus created
respectively by the lower layer reflection light component creating
section, diffuse reflection light component creating section, and
the components which are created respectively by the colorant
material particle reflection light component creating section and
the surface reflection light component creating section and whose
mixing ratio is decided by the shape parameter calculating
section.
[0335] With this arrangement, it is possible to accurately simulate
specular gloss of a sample having a colorant material layer
containing colorant material particles relatively large in diameter
(that is, in case where the colorant material particles are
pigment). Moreover, with this arrangement, it is possible to
simulate, with sufficient accuracy, the specular gloss of the
sample in a geometry having a large zenith angle which glossiness
becomes higher for a low-gloss image and the simulation accuracy
cannot be sufficient even if the lower layer reflection light
component and internal reflection light component are taken in
consideration.
[0336] The specular gloss simulating device may be preferably
arranged such that the surface reflection light component creating
section uses a Torrance-Sparrow model as the Bidirectional
Reflectance Distribution Function, and uses, in the
Torrance-Sparrow model, a variable of surface roughness of the
sample as a parameter for defining an extent of a reflection light
component.
[0337] Here, what is meant by the "variable of the roughness of the
surface shape of the sample" is a standard deviation (distribution
range) of slopes of facets, the standard deviation being calculated
with a range of 2 s (about 95.5% of data) from information of
height of top surfaces (a boundary between the surface of the
colorant material layer and the air layer) of the sample where the
information of the height of the top surfaces is the length along
the Z axis when the sample is positioned in a XYZ coordinate space
(see FIG. 5).
[0338] With this arrangement, the use of Torrance-Sparrow model
which is on assumption that the light is scattered anisotropically
allows highly-accurate calculation of the surface reflection light
component. Moreover, the Torrance-Sparrow model is easy to use
because it requires a small number of other parameters. Further, if
the variable in the roughness of the surface shape of the sample is
used as the parameter for defining the extent of the reflection
light component, the Torrance-Sparrow model can be used with high
accuracy.
[0339] The specular gloss simulating device may be preferably
arranged such that the colorant material particle reflection light
component creating section uses a Torrance-Sparrow model as the
Bidirectional Reflectance Distribution Function, and uses, in the
Torrance-Sparrow model, a variable of density distribution evenness
of the sample as a parameter for defining an extent of a reflection
light component.
[0340] Here, the "variable of density distribution evenness" is a
standard deviation (distribution range) of transmission density
calculated with a range of 2 s (about 95.5% of data) from the
histogram of the density of each pixel of transmission image of the
sample (the transmission image is an image taken, in the space the
sample is positioned in a XYZ coordinate space (see FIG. 5), for
example, where a camera (light receiver) is positioned on the
positive side of the Z axis and the light source is positioned on
the negative side of the Z axis)
[0341] With this arrangement, the use of Torrance-Sparrow model
which is on assumption that the light is anisotropically scattered
allows highly-accurate calculation of the colorant material
particle reflection light component. Moreover, the Torrance-Sparrow
model is easy to use because it requires a small number of other
parameters. Further, if the variable of the evenness in density of
the sample as the parameter for defining the extent of the
reflection light component, the Torrance-Sparrow model can be used
with high accuracy.
[0342] As described above, another specular gloss simulating device
according to the present invention for simulating specular gloss by
measuring, in a given geometry, luminance of a sample that has a
base material and a colorant material layer which is formed on the
base material and contains colorant material particles, and then
simulating a specular reflection light amount in an other geometry
from the thus measured luminance, is arranged to include: a lower
layer reflection light component creating section for calculating
lower layer reflection light components in the given geometry and
the other geometry from base material luminance, where the base
material luminance is luminance of only the base material measured
in a plurality of geometries, and the lower layer reflection light
component is a component being reflected on the base material and
transmitting through and out of the colorant material layer; an
upper layer reflection light component creating section for
calculating a diffuse reflection light component, a colorant
material particle reflection light component, and a surface
reflection light component in the other geometry from the luminance
of the sample measured in the given geometry and the lower layer
reflection light component in the given geometry, the lower layer
reflection light component being calculated out by the lower layer
reflection light component creating section, where the diffuse
reflection light component is a component being diffused among the
colorant material particles contained in the colorant material
layer and transmitting out of the colorant material layer, the
colorant material particle reflection light component is a
component being reflected on the colorant material particles, and
the surface reflection light component is a component being
reflected on a surface of the colorant material layer; and a
specular reflection light amount calculating section for
calculating out a specular reflection light amount of the sample in
the other geometry from the components in the other geometry which
are thus calculated out by the lower layer reflection light
component creating section and the upper layer reflection light
component creating section. With the above arrangement, the
simulation of the specular gloss is carried out by obtaining the
specular reflection light amount of the sample by effectively using
the Bidirectional Reflectance Distribution Function model, taking
the lower layer reflection light component and the internal
reflection light component, as well as the surface reflection light
component, into consideration. This makes it possible to calculate
out the specular gloss with high accuracy for low-density image
sample and low-gloss image sample for which accurate calculation of
the specular gloss cannot be done with the conventional art.
[0343] The another specular gloss simulating device according to
the present invention may be preferable arranged such that the
upper reflection light component creating section calculates out
the diffuse reflection light component, the colorant material
particle reflection light component, and the surface reflection
light component in the other geometry by using a Bidirectional
Reflectance Distribution Function model.
[0344] The use of the Bidirectional Reflectance Distribution
Function model makes it possible for the upper layer reflection
light component creating section to obtain the diffuse reflection
light component, colorant material particle reflection light
component, and surface reflection light component with accuracy,
and consequently makes it possible to evaluate the specular
glossiness with high accuracy.
[0345] The another specular gloss simulating device may be
preferably arranged such that the lower layer reflection light
component creating section calculates out the lower layer
reflection light components in the other geometry and at least
three kinds of the given geometries; the upper layer reflection
light component creating section includes: a parameter calculating
section for deciding (a) a parameter to be used in the Oren-Nayar
model, and (b) a mixing ratio among the diffuse reflection light
component, the colorant material particle reflection light
component, and the surface reflection light component, from (i)
luminance of the sample measured in the at least three kinds of the
given geometries, and (ii) the lower layer reflection light
components in the at least three kinds of the given geometries, the
lower layer reflection light components being calculated by the
lower layer reflections light component creating section; and a
reflection light component calculating section for calculating the
colorant material particle reflection light component and the
surface reflection light component in the other geometry according
to the mixing ratio, and calculating the diffuse reflection light
component in the other geometry according to the mixing ratio and
from the parameter by using the Oren-Nayar model.
[0346] The mixing ratio among the diffuse reflection light
component, colorant material particle reflection light component,
and surface reflection light component, which are contained in the
reflection light component can be expressed with two parameter
where the entire reflection light component is put as 1. Moreover,
for calculating out the diffuse reflection light component by using
the Oren-Nayar model, it is necessary to find an unknown parameter
that describes a reflection ratio of the facet.
[0347] In this arrangement, for obtaining the reflection light
components of the upper layer reflection light, the parameter
calculating section uses the density of the sample measured in the
at least three given geometries, and the lower layer reflection
light components in the at least three given geometries. The upper
layer reflection light component is obtained by subtracting the
lower layer reflection light component from the specular reflection
light component from the lower layer reflection light component.
Therefore, three conditional equations as to the at least three
given geometries can be created. With the three conditional
equations, the unknown parameter in the Oren-Nayar model and two
parameter that describes the mixing ratio. That is, it is possible
to obtain, without approximation, the components contained in the
upper reflection light component. Therefore, it is possible to
accurately obtain the diffuse reflection light component, colorant
material particle reflection light component, and surface
reflection light component contained in the upper layer reflection
light component, and consequently, it is possible to evaluate the
specular glossiness with high accuracy.
[0348] The another specular gloss simulating device according to
the present invention may be preferably arranged such that the
reflection light component calculating section calculates the
colorant material particle reflection light component and the
surface reflection light component in the other geometry according
to the mixing ratio and by using the Torrance-Sparrow model.
[0349] The use of the Torrance-Sparrow model makes it possible to
accurately obtain the colorant material particles reflection light
component and the surface reflection light component contained in
the upper layer reflection light component. Consequently, it
becomes possible to evaluate the specular gloss with high
accuracy.
[0350] The any of the (another) specular gloss simulating device
may be controlled by a computer. Thus, the scope of the present
invention encompasses a computer-readable recording medium in which
a control program is stored, the control program being for
operating the (another) specular gloss simulating device and the
control program causing a computer to function as each of the
sections.
[0351] With the control program according to the present invention
the control function of the specular gloss simulating device having
any of these arrangement can be realized with a computer. Moreover,
the recording medium according to the present invention is a
recording medium in which the control program is stored. As a
result, it is possible to provide the portable recording medium
storing the control program for carrying out the specular
simulation method of the present invention.
[0352] The invention being thus described, it will be obvious that
the same way may be varied in many ways. Such variations are not to
be regarded as a departure from the spirit and scope of the
invention, and all such modifications as would be obvious to one
skilled in the art are intended to be included within the scope of
the following claims.
* * * * *